Compositions for regulating iron homeostasis and methods of using same

ABSTRACT

The present disclosure relates to hemojuvelin-IgG Fc domain fusion proteins, variants, derivatives, fragments and peptide mimetics derived therefrom and methods of using these fusion proteins for the regulation of iron homeostasis and the treatment of diseases related to iron homeostasis.

RELATED APPLICATIONS

This application is a 35 U.S.C. §371 filing of International ApplicationNo. PCT/US2012/021829, filed Jan. 19, 2012; which claims priority toU.S. Provisional Patent Application No. 61/434,405 filed on Jan. 19,2011. The entire contents of which are incorporated herein by reference.

RELATED APPLICATION

This application claims priority from U.S. Provisional PatentApplication No. 61/434,405, filed on Jan. 19, 2011 and incorporatedherein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to therapy, prevention andamelioration of iron homeostasis disorders, particularly with respect tomanagement of anemias. The present disclosure is more specificallyrelated to hemojuvelin-immunoglobulin Fc domain fusion proteins andvariants, derivatives and peptide mimetics derived therefrom and methodsof using these compositions for altering serum iron, serum hemoglobinand/or hematocrit levels in humans.

BACKGROUND

Iron is an essential element required for growth and survival of almostevery organism. Red blood cells (RBC) contain hemoglobin (Hb), a red,iron-rich protein that carries oxygen from the lungs to all of thebody's muscles and organs where it reacts to provide the energy the bodyneeds for its normal activities. When the number of red blood cells orthe amount of hemoglobin they contain fall below normal, the bodyreceives less oxygen and generates less energy than it needs to functionproperly. This condition in general is referred to as anemia. A commoncause for anemia among infants and children is an iron deficiency. Asmany as 20% of children in the United States and 80% of children indeveloping countries will become anemic at some point by the age of 18years. Martin, P. L., et al. The Anemias, Principles and Practices ofPediatrics, 1657 (2d ed., Lippincott 1994).

In mammals, the iron balance is primarily regulated at the level ofduodenal absorption of dietary iron. In humans, hereditaryhemochromatosis (HH) is a common autosomal recessive genetic diseasecaused by hyperabsorption of dietary iron leading to an iron overload inplasma and multiple organs, including in particular the pancreas, liver,and skin, and resulting in damages in these organs and tissues due tothe iron deposits.

Juvenile hemochromatosis is an iron overload disorder caused bymutations in the gene encoding the major iron regulatory hormonehepcidin (HAMP) and hemojuvelin (HFE2). (Roetto, A., et al. 2003. Nut.Genet. 33:21-22; Papanikolaou, G., et al. 2004. Nut. Genet. 36:77-82.)It has been shown that hemojuvelin is a bone morphogenetic protein (BMP)co-receptor and that hemojuvelin-mediated BMP signals regulate hepcidinexpression and iron metabolism. (Babitt, J. L., et al. 2006. Nat. Genet.38:531-539; Babitt, J. L., et al. 2007. J Clin Invest. 117:1933-1939.)However, the endogenous BMP regulator(s) of hepcidin in vivo is unknown.

Hemojuvelin (also known as RGMc) is a member of the Repulsive GuidanceMolecules family of proteins, including RGMa and DRAGON (RGMb), whichshare 50-60% amino acid identity. (Samad, T. A., et al. 2004. J.Neurosci. 24:2027-2036.).

There is a need for a cost-effective and efficient method for regulatinghepcidin expression and iron metabolism.

SUMMARY

The present disclosure provides hemojuvelin (“HJV”)-immunoglobulin Fcdomain fusion proteins. The present disclosure also provides methods ofusing these proteins for the treatment of iron homeostasis disorders.The HJV may be mammalian HJV. More specifically, the HJV may be mouse orhuman HJV.

The present disclosure further provides a composition comprising afusion protein or a variant, derivative or peptide mimetic derivedtherefrom 95% identical to the sequence of SEQ ID NO:9. In oneembodiment, the fusion protein or a variant, derivative or peptidemimetic derived therefrom is at least 98% pure as determined by sizeexclusion chromatography. In another embodiment, the fusion protein or avariant, derivative or peptide mimetic derived therefrom isglycosylated. In certain embodiments, asparagine 83, asparagine 178 andasparagine 337 of SEQ ID NO. 1 and SEQ ID NO. 9 are N-glycoslyationsites. In one aspect of this embodiment, the glycosylation pattern is amammalian glycosylation pattern. Specifically, the glycosylation patternis from a Chinese hamster ovary (CHO) cell line.

In another embodiment, the N-terminal amino acid of the fusion proteinor a variant, derivative or peptide mimetic derived therefrom isglutamine. In one aspect of this embodiment, the N-terminus of thefusion protein or a variant, derivative or peptide mimetic derivedtherefrom is QCKILRCNAE (SEQ ID NO:10). In another embodiment, theN-terminal fragment may be any fragment from the first 150 amino acidsof SEQ ID NOs: 1 or 9.

In another embodiment, the composition is substantially pyrogen free. Inanother embodiment, the serum half-life of the fusion protein or avariant, derivative or peptide mimetic derived therefrom is at least 10hours. In another embodiment, the fusion protein or a variant,derivative or peptide mimetic derived therefrom binds to bonemorphogenic protein-6 (“BMP-6”) with a K_(D) of at least 10⁻⁷ M andinhibits BMP-6 signaling. In another embodiment, the compositionincreases hematocrit in a subject when administered. In anotherembodiment, the composition increases hematocrit to at least normallevels in an anemic subject when administered to the anemic subject forone month or more.

In another embodiment, the fusion protein or a variant, derivative orpeptide mimetic derived therefrom forms a homodimer. In one aspect ofthis embodiment, the homodimer is formed in the Fc hinge region. Morespecifically, the homodimer is formed through a chemical interactionbetween cysteines 373, 380 and/or 383, in SEQ ID NO:9. Specifically, thechemical interaction is a disulfide bond.

The present disclosure also provides a nucleic acid molecule thatencodes the fusion protein or a variant, derivative, fragment or peptidemimetic derived therefrom. In one embodiment, the nucleic acid moleculecomprises a sequence 95% identical to the sequence of SEQ ID NO:11.

The present disclosure also provides a mammalian cell comprising thenucleic acid sequence that encodes the fusion protein or a variant,derivative, fragment or peptide mimetic derived therefrom. In oneembodiment, the cell is a CHO cell.

The present disclosure also provides a method of treating an ironhomeostasis disorder with resultant anemia in a subject in need thereofby administering a therapeutically effective amount of the compositiondescribed above to the subject, thereby treating the iron homeostasisdisorder and improving anemia.

The present disclosure also provides a composition comprising a fusionprotein or a variant, derivative, fragment or peptide mimetic derivedtherefrom wherein the fusion protein or a variant, derivative, fragmentor peptide mimetic derived therefrom comprises an N-terminal polypeptideand a C-terminal polypeptide, wherein the N-terminal polypeptidecomprises a sequence 95% identical to the sequence of SEQ ID NO: 1 andwherein the C-terminal peptide comprises a sequence 95% identical to asequence selected from the group consisting of SEQ ID NOs: 3, 4, 5, 6,and 7. In one embodiment, the fusion protein or a variant, derivative,fragment or peptide mimetic derived therefrom is at least 98% pure asdetermined by size exclusion chromatography.

In another embodiment, the fusion protein or a variant, derivative,fragment or peptide mimetic derived therefrom is glycosylated. In oneaspect of this embodiment, the glycosylation pattern is a mammalianglycosylation pattern. Specifically, the glycosylation pattern is from aChinese hamster ovary (CHO) cell line.

In another embodiment, the N-terminal amino acid of the fusion proteinor a variant, derivative, fragment or peptide mimetic derived therefromis glutamine. In one aspect of this embodiment, the N-terminus of thefusion protein or a variant, derivative, fragment or peptide mimeticderived therefrom is QCKILRCNAE (SEQ ID NO:10).

In another embodiment, the composition is substantially pyrogen free. Inanother embodiment, the serum half-life of the fusion protein or avariant, derivative or peptide mimetic derived therefrom is at least 10hours. In another embodiment, the fusion protein or a variant,derivative or peptide mimetic derived therefrom binds to bonemorphogenic protein-6 (“BMP-6”) with a K_(D) of at least 10⁻⁷ M andinhibits BMP-6 signaling. In another embodiment, the compositionincreases hematocrit in a subject when administered. In anotherembodiment, the composition increases hematocrit to at least normallevels in an anemic subject when administered to the anemic subject forone month or more.

The present disclosure also provides a nucleic acid molecule thatencodes the fusion protein or a variant, derivative, fragment or peptidemimetic derived therefrom. In one embodiment, the nucleic acid sequencecomprises SEQ ID NO:11.

The present disclosure also provides a mammalian cell comprising thenucleic acid sequence that encodes the fusion protein or a variant,derivative, fragment or peptide mimetic derived therefrom. In oneembodiment, the cell is a CHO cell.

The present disclosure also provides a method of treating an ironhomeostasis disorder and/or improving anemia in a subject in needthereof by administering a therapeutically effective amount of thecomposition described above to the subject, thereby treating the ironhomeostasis disorder and/or improving anemia.

The present disclosure also provides a method of treating a cancer in asubject in need thereof by administering a therapeutically effectiveamount of the composition described above to the subject, therebytreating the cancer.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an alignment of the amino acid sequences of SEQ ID NOs 3-7.

FIG. 2 shows a schematic of an HJV.Fc dimer.

FIG. 3 is a line graph showing serum hemoglobin levels in anemic ratsadministered 20 mg/kg of HJV.Fc compared to control rats.

FIG. 4 is a line graph showing serum hemoglobin levels in anemic ratsadministered 2 or 20 mg/kg of HJV.Fc compared to control rats.

FIG. 5 is a bar graph that shows hematocrit levels in anemic ratsadministered 20 mg/kg of HJV.Fc compared to control rats.

FIG. 6 is a bar graph showing serum iron in anemic rats administered 20mg/kg of HJV.Fc compared to control rats.

FIG. 7A is a graph showing HJV.His (homodimer) affinity using data fromBiacore binding assay to BMP6.

FIG. 7B is a graph showing HJV.Fc (homodimer) affinity using data fromBiacore binding assay to BMP6.

FIG. 8 shows HJV.Fc is effective in inhibiting BMP6 activity in acell-based bioinhibition assay.

FIG. 9 shows a preparation of >95% purity of monomers of the homodimericHJV.Fc by HPLC analysis.

DETAILED DESCRIPTION

The inventors have found new therapeutic compositions for the treatmentof anemia. These compositions are fusion proteins comprising hemojuvelin(“HJV”) and an IgG Fc region and variants, derivatives, fragments andpeptide mimetics derived therefrom. The present disclosure providesfusion proteins comprising a peptide comprising at least a portion ofthe amino acid sequence of HJV fused to an IgG Fc region or a derivativethereof. In certain embodiments, the HJV portion of the fusion proteinis the N-terminal portion of the fusion protein and the IgG Fc portionof the fusion protein is the C-terminal portion. In other embodiments,the HJV portion of the fusion protein is the C-terminal portion of thefusion protein and the IgG Fc portion of the fusion protein is theN-terminal portion.

In certain embodiments, the N-terminal and C-terminal portions of thefusion protein are joined with a linker. In specific embodiments, thelinker is a polypeptide between 1 and 50 amino acids in length. In morespecific embodiments, the linker is between 2 and 25 amino acids inlength. In more specific embodiments, the linker is between 3 and 15amino acids in length. In more specific embodiments, the linker is 4, 5,6, 7, 8 or 9 amino acids in length. In one preferred embodiment, thelinker is 5 amino acids in length. In certain embodiments, a linker maybe rich in glycine and proline residues and my, for example, contain asingle sequence of threonine/serine and glycines or repeating sequencesof threonine/serine and glycine (e.g. TG). In certain embodiments,mutations may be made in the linker (if any) and or the Fc protein toalter the half-life of the protein.

Administration of the fusion proteins of the present disclosure orvariants, derivatives, fragments and peptide mimetics derived therefromresults in decreased hepcidin expression. The compositions describedherein can be used to treat iron metabolism disorders and to increaseserum hemoglobin and hematocrit.

The HJV Portion

The human hemojuvelin (“HJV”) portion of the fusion protein describedherein comprises a soluble portion of HJV that is able to increasemobilization of iron and/or treat or ameliorate at least one symptomassociated with an iron metabolism disease. In some embodiments, the HJVportion of the fusion protein of the present disclosure is at least 75%(e.g., at least 80%, at least 85%, at least 90%, at least 95%, at least96%, at least 97%, at least 98%, or at least 99%) identical to a portionof SEQ ID NO:1.

The amino acid sequence of HJV is shown in Table 1 below:

TABLE 1 Amino acid sequence of human HJV without the N-terminal signalsequence or C-terminal GPI domain (364 amino acids; SEQ ID NO: 1) 10 2030 40 50 60 QCKILRCNAE YVSSTLSLRG GGSSGALRGG GGGGRGGGVG SGGLCRALRS YALCTRRTAR 70 80 90 100 110 120 TCRGDLAFHS AVHGIEDLMI QHNCSRQGPT APPPPRGPAL PGAGSGLPAP DPCDYEGRFS 130 140 150 160 170 180 RLHGRPPGFLHCASFGDPHV RSFHHHFHTC  RVQGAWPLLD NDFLFVQATS SPMALGANAT 190 200 210 220230 240 ATRKLTIIFK NMQECIDQKV YQAEVDNLPV AFEDGSINGG DRPGGSSLSIQTANPGNHVE 250 260 270 280 290 300 IQAAYIGTTI IIRQTAGQLS FSIKVAEDVAMAFSAEQDLQ  LCVGGCPPSQ RLSRSERNRR 310 320 330 340 350 360 GAITIDTARRLCKEGLPVED AYFHSCVFDV  LISGDPNFTV AAQAALEDAR  AFLPDLEKLH 364 LFPS

In certain embodiments, the HJV portion of the fusion protein describedherein is any fragment of SEQ ID NO:1 that is soluble in aqueoussolution and is able to mobilize iron and/or treat or ameliorate atleast one symptom associated with an iron metabolism disease. Fragmentsof SEQ ID NO:1 that make up the HJV portion of the fusion protein of thepresent disclosure include fragments of 10, 20, 30, 40, 50, 60, 70, 80,90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220,230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350 or 360amino acids of SEQ ID NO:1. These fragments can comprise any range ofamino acids of SEQ ID NO:1. In some specific embodiments, fragmentscomprise 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140 or150 amino acids of amino acids 1-150 of SEQ ID NO:1. In certainembodiments, the HJV portion of the fusion protein of the presentdisclosure has greater than 80, 85, 90, 95, 97, 98, or 99% identity tothe fragments of SEQ ID NO:1, wherein the fragments include 10, 20, 30,40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180,190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320,330, 340, 350 or 360 amino acids of SEQ ID NO:1.

Fragments of SEQ ID NO:1 that make up the HJV portion of the fusionprotein of the present disclosure include fragments of 10, 20, 30, 40,50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190,200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330,340, 350 or 360 consecutive amino acids of SEQ ID NO:1. In certainembodiments, the HJV portion of the fusion protein of the presentdisclosure has greater than 80, 85, 90, 95, 97, 98, or 99% identity tothe fragments of SEQ ID NO:1, wherein the fragments include 10, 20, 30,40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180,190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320,330, 340, 350 or 360 consecutive amino acids of SEQ ID NO:1.

In certain embodiments, the HJV portion of the fusion protein of thepresent disclosure is full length or a fragment and has greater than 75%identity to SEQ ID NO:1. In other embodiments, the HJV portion of thefusion protein of the present disclosure is full length or a fragmentand has greater than 80, 85, 90, 95, 97, 98, or 99% identity to SEQ IDNO:1. In certain specific embodiments, the differences between SEQ IDNO:1 and the HJV portion of the fusion protein of the present disclosureare conservative amino acid changes, as described below.

The IgG Fc Portion

The IgG Fc portion of the fusion protein of the present disclosurecomprises at least a portion of the Fc region of an immunoglobulin or aderivative thereof which, when fused with the HJV portion of the fusionprotein of the present disclosure, is able to mobilize iron and/or treator ameliorate at least one symptom associated with an iron metabolismdisease. The IgG Fc portion of the fusion protein of the presentdisclosure stabilized the fusion protein when administered to a subject.In specific embodiments, the attachment of an IgG Fc or variant,derivative, fragment or peptide mimetic derived therefrom makes theserum half-life of the serum protein greater than 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, 14, 15, 15, 17, 18, 19, 20, 21, 22, 23, 24, 36,48, 60, 72, 84, or 96 hours. There are several sequences compatible withthe fusion protein of the present disclosure.

In certain embodiments, the IgG Fc domain includes CH2 and CH3 domainsand a hinge region. In other embodiments, the IgG Fc also contains atleast a portion of the CH1 region. In specific embodiments, the HJVportion of the fusion protein is directly linked to the hinge region. Inother embodiments, the Fc domain contains sequence N-terminal to thehinge region from its CH1 domain which is linked to the HJV portion ofthe fusion protein. In other embodiments, a linker is attached to thehinge region, or the CH1 domain on the Fc domain. In more specificembodiments, the hinge region comprises 4 amino acids with the consensussequence X₁-P-X₂-X₃ (SEQ ID NO:2), wherein X₁ is cysteine or serine, X₂is leucine or proline, and X₃ is cysteine or serine. The hinge region ofan intact immunoglobulin provides the protein sufficient flexibility foreffective antigen-antibody binding. In certain embodiments of thepresent disclosure, the hinge region is included in the IgG Fc portionof the fusion protein of the present disclosure to maintain itsflexibility, especially when the fusion protein is in the dimer form.

In certain embodiments, the IgG Fc portion of the fusion protein of thepresent disclosure is at least 75% (e.g., at least 80%, at least 85%, atleast 90%, at least 95%, at least 96%, at least 97%, at least 98%, or atleast 99%) identical to a portion of SEQ ID NO:3.

TABLE 2 Amino acid sequence of an IgG Fc region derivative (232 amino acids; SKI ID NO: 3) 10 20 30 40 50 60 DPKSCDKPHT CPLCPAPELLGGPSVFLFPP  KPKDTLMISR TPEVTCVVVD VSHEDPEVKF 70 80 90 100 110 120NWYVDGVEVH NAKTKPREEQ YNSTYRVVSV LTVLHQDWLN GKEYKCKVSN KALPAPIEKT 130140 150 160 170 180 ISKAKGQPRE PQVYTLPPSR DELTKNQVSL TCLVKGFYPSDIAVEWESNG QPENNYKATP 190 200 210 220 230  232 PVLDSDGSFF LYSKLTVDKSRWQQGNVFSC SVMHEALHNH YTQKSLSLSP GK

In certain embodiments, the IgG Fc portion of the fusion protein of thepresent disclosure is any fragment of SEQ ID NO:3 which, when fused withthe HJV portion of the fusion protein of the present disclosure, issoluble in aqueous solution and is able to mobilize iron and/or treat orameliorate at least one symptom associated with an iron metabolismdisease. Fragments of SEQ ID NO:3 that make up the IgG Fc portion of thefusion protein of the present disclosure include fragments of 10, 20,30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180,190, 200, 210, 220 or 230 amino acids of SEQ ID NO:3. In certainembodiments, the IgG Fc portion of the fusion protein of the presentdisclosure has greater than 80, 85, 90, 95, 97, 98, or 99% identity tothe fragments of SEQ ID NO: 3, wherein the fragments include 10, 20, 30,40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180,190, 200, 210, 220, or 230 amino acids of SEQ ID NO: 3.

Fragments of SEQ ID NO:3 that make up the IgG Fc portion of the fusionprotein of the present disclosure include fragments of 10, 20, 30, 40,50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190,200, 210, 220 or 230 consecutive amino acids of SEQ ID NO:3. In certainembodiments, the IgG Fc portion of the fusion protein of the presentdisclosure has greater than 80, 85, 90, 95, 97, 98, or 99% identity tothe fragments of SEQ ID NO:3, wherein the fragments include 10, 20, 30,40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180,190, 200, 210, 220, or 230 consecutive amino acids of SEQ ID NO: 3.

In certain embodiments, the IgG Fc portion of the fusion protein of thepresent disclosure is full length or a fragment and has greater than 75%identity to SEQ ID NO:3. In other embodiments, the IgG Fc portion of thefusion protein of the present disclosure is full length or a fragmentand has greater than 80, 85, 90, 95, 97, 98, or 99% identity to SEQ IDNO:3. In certain specific embodiments, the differences between SEQ IDNO:3 and the IgG Fc portion of the fusion protein of the presentdisclosure are conservative amino acid changes, as described below.

Other sequences or fragments of derivatives thereof are compatible foruse as the IgG Fc portion of the fusion protein of the presentdisclosure. An alignment of the IgG Fc derivative (SEQ ID NO:3), humanIgG1 Fc (SEQ ID NO:4), the Fc region from the VEGFR-Fc fusion developedby Regeneron (SEQ ID NO:5), the Fc region from the CTLA4-Fc fusion(ORENCIA™ or abatacept) developed by Bristol Myers Squibb (SEQ ID NO:6),the Fc region from the IL 1R-Fc fusion (ARCALYST™ or rilonacept)developed by Regeneron (SEQ ID NO:7) and the Fc region from HUMIRA®(adaluminab).

In certain embodiments, the IgG Fc portion of the fusion protein of thepresent disclosure is any fragment of SEQ ID NOs:4, 5, 6 or 7 which,when fused with the HJV portion of the fusion protein of the presentdisclosure, is soluble in aqueous solution and is able to mobilize ironand/or treat or ameliorate at least one symptom associated with an ironmetabolism disease. Fragments of SEQ ID NOs:4, 5, 6 or 7 that make upthe IgG Fc portion of the fusion protein of the present disclosureinclude fragments of 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120,130, 140, 150, 160, 170, 180, 190, 200, 210, 220 or 230 amino acids ofSEQ ID NOs:4, 5, 6 or 7. In certain embodiments, the IgG Fc portion ofthe fusion protein of the present disclosure has greater than 80, 85,90, 95, 97, 98, or 99% identity to the fragments of SEQ ID NO:3, whereinthe fragments include 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120,130, 140, 150, 160, 170, 180, 190, 200, 210, 220, or 230 amino acids ofSEQ ID NOs:4, 5, 6 or 7.

Fragments of SEQ ID NOs:4, 5, 6 or 7 that make up the IgG Fc portion ofthe fusion protein of the present disclosure include fragments of 10,20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170,180, 190, 200, 210, 220 or 230 consecutive amino acids of SEQ ID NOs:4,5, 6 or 7. In certain embodiments, the IgG Fc portion of the fusionprotein of the present disclosure has greater than 80, 85, 90, 95, 97,98, or 99% identity to the fragments of SEQ ID NO:3, wherein thefragments include 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120,130, 140, 150, 160, 170, 180, 190, 200, 210, 220, or 230 consecutiveamino acids of SEQ ID NOs:4, 5, 6 or 7.

In certain embodiments, the IgG Fc portion of the fusion protein of thepresent disclosure is full length or a fragment and has greater than 75%identity to SEQ ID NOs:4, 5, 6 or 7. In other embodiments, the IgG Fcportion of the fusion protein of the present disclosure is full lengthor a fragment and has greater than 80, 85, 90, 95, 97, 98, or 99%identity to SEQ ID NOs:4, 5, 6 or 7. In certain specific embodiments,the differences between SEQ ID NOs:4, 5, 6 or 7 and the IgG Fc portionof the fusion protein of the present disclosure are conservative aminoacid changes, as described below.

The Linker

In certain embodiments, the fusion protein of the present disclosureincludes a linker connecting the HJV portion and the IgG Fc portion ofthe fusion protein. In preferred embodiments, the linker is a peptide.In alternative embodiments, the peptide can be 3, 4, 5, 6, 7, 8, 9, 10,11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,47, 48, 49 and 50 amino acids in length. In certain embodiments, theamino acids making up the linker are glycine or serine at each position.In one preferred embodiment, the linker has the sequence GGGGG (SEQ IDNO:8).

In certain embodiments, a linker may be rich in glycine and prolineresidues and my, for example, contain a single sequence ofthreonine/serine and glycines or repeating sequences of threonine/serineand glycine (e.g. TG).

In certain embodiments, mutations may be made in the linker (if any) andor the Fc protein to alter the half-life of the protein.

Dimerization

In certain embodiments, the fusion protein is in the form of a dimerincluding two identical polypeptide subunits. In the embodiment shownschematically in FIG. 2, each polypeptide subunit, from the N-terminalto C-terminal, includes the polypeptide sequence of SEQ ID NO:9, shownbelow.

TABLE 3 Amino acid sequence of an HJV.Fc fusion protein of the  invention (596 amino acids; SEQ ID NO: 9) 10 20 30 40 50 60 QCKILRCNAEYVSSTLSLRG GGSSGALRGG GGGGRGGGVG  SGGLCRALRS  YALCTRRTAR 70 80 90 100110 120 TCRGDLAFHS AVHGIEDLMI QHNCSRQGPT  APPPPRGPAL  PGAGSGLPAPDPCDYEGRFS 130 140 150 160 170 180 RLHGRPPGFL HCASFGDPHV  RSFHHHFHTCRVQGAWPLLD NDFLFVQATS SPMALGANAT 190 200 210 220 230 240 ATRKLTIIFK NMQECIDQKV  YQAEVDNLPV AFEDGSINGG  DRPGGSSLSI  QTANPGNHVE 250 260 270280 290 300 IQAAYIGTTI IIRQTAGQLS FSIKVAEDVA MAFSAEQDLQ LCVGGCPPSQRLSRSERNRR 310 320 330 340 350 360 GAITIDTARR LCKEGLPVED AYFHSCVFDVLISGDPNFTV AAQAALEDAR  AFLPDLEKLH 370 380 390 400 410 420 LFPSDPKSCDKPHTCPLCPA PELLGGPSVF LFPPKPKDTL MISRTPEVTC VVVDVSHEDP 430 440 450 460470 480 EVKFNWYVDG VEVHNAKTKP REEQYNSTYR  VVSVLTVLHQ DWLNGKEYKCKVSNKALPAP 490 500 510 520 530 540 IEKTISKAKG QPREPQVYTL PPSRDELTKNQVSLTCLVKG FYPSDIAVEW ESNGQPENNY 550 560 570 580 590 594 KATPPVLDSDGSFFLYSKLT VDKSRWQQGN VFSCSVMHEA LHNHYTQKSL SLSPGK

The two polypeptide subunits are connected together by disulfide bondsbetween the respective hinge regions to form the dimer structure. Thehomodimer can be formed in the Fc hinge region. More specifically, thehomodimer can be formed through a chemical interaction between cysteines373, 380 and/or 383, in SEQ ID NO:9.

The nucleic acid sequence of the vector used to express a protein withan amino acid sequence of SEQ ID NO:9 is shown below.

TABLE 4 Nucleic acid sequence of vector that encodes SEQ ID NO: 9.(SEQ ID NO: 11)ttctagagaa tccagacatg ataagataca ttgatgagtt tggacaaacc acaactagaa 60tgcagtgaaa aaaatgcttt atttgtgaaa tttgtgatgc tattgcttta tttgtaacca 120ttataagctg caataaacaa gttaacaaca acaattgcat tcattttatg tttcaggttc 180agggggaggt gtgggaggtt ttttaaagca agtaaaacct ctacaaatgt ggtatggctg 240attatgatca atcgatgtcg accaattcgt aatcatgtca tagctgtttc ctgtgtgaaa 300ttgttatccg ctcacaattc cacacaacat acgagccgga agcataaagt gtaaagcctg 360gggtgcctaa tgagtgagct aactcacatt aattgcgttg cgctcactgc ccgctttcca 420gtcgggaaac ctgtcgtgcc agctgcatta atgaatcggc caacgcgcgg ggagaggcgg 480tttgcgtatt gggcgctctt ccgcttcctc gctcactgac tcgctgcgct cggtcgttcg 540gctgcggcga gcggtatcag ctcactcaaa ggcggtaata cggttatcca cagaatcagg 600ggataacgca ggaaagaaca tgtgagcaaa aggccagcaa aaggccagga accgtaaaaa 660ggccgcgttg ctggcgtttt tccataggct ccgcccccct gacgagcatc acaaaaatcg 720acgctcaagt cagaggtggc gaaacccgac aggactataa agataccagg cgtttccccc 780tggaagctcc ctcgtgcgct ctcctgttcc gaccctgccg cttaccggat acctgtccgc 840ctttctccct tcgggaagcg tggcgctttc tcatagctca cgctgtaggt atctcagttc 900ggtgtaggtc gttcgctcca agctgggctg tgagcacgaa ccccccgttc agcccgaccg 960ctgcgcctta tccggtaact atcgtcttga gtccaacccg gtaagacacg acttatcgcc 1020actggcagca gccactggta acaggattag cagagcgagg tatgtaggcg gtgctacaga 1080gttcttgaag tggtggccta actacggcta cactagaaga acagtatttg gtatctgcgc 1140tctgctgaag ccagttacct tcggaaaaag agttggtagc tcttgatccg gcaaacaaac 1200caccgctggt agcggtggtt tttttgtttg caagcagcag attacgcgca gaaaaaaagg 1260atctcaagaa gatcctttga tcttttctac ggggtctgac gctcagtgga acgaaaactc 1320acgttaaggg attttggtca tgagattatc aaaaaggatc ttcacctaga tccttttaaa 1380ttaaaaatga agttttaaat caatctaaag tatatatgag taaacttggt ctgacagtta 1440ccaatgctta atcagtgagg cacctatctc agcgatctgt ctatttcgtt catccatagt 1500tgcctgactc cccgtcgtgt agataactac gatacgggag ggcttaccat ctggccccag 1560tgctgcaatg ataccgcgag acccacgctc accggctcca gatttatcag caataaacca 1620gccagccgga agggccgagc gcagaagtgg tcctgcaact ttatccgcct ccatccagtc 1680tattaattgt tgccgggaag ctagagtaag tagttcgcca gttaatagtt tgcgcaacgt 1740tgttgccatt gctacaggca tcgtggtgtc acgctcgtcg tttggtatgg cttcattcag 1800ctccggttcc caacgatcaa ggcgagttac atgatccccc atgttgtgca aaaaagcggt 1860tagctccttc ggtcctccga tcgttgtcag aagtaagttg gccgcagtgt tatcactcat 1920ggttatggca gcactgcata attctcttac tgtcatgcca tccgtaagat gcttttctgt 1980gactggtgag tactcaacca agtcattctg agaatagtgt atgcggcgac cgagttgctc 2040ttgcccggcg tcaatacggg ataataccgc gccacatagc agaactttaa aagtgctcat 2100cattggaaaa cgttcttcgg ggcgaaaact ctcaaggatc ttaccgctgt tgagatccag 2160ttcgatgtaa cccactcgcg cacccaactg atcttcagca tcttttactt tcaccagcgt 2220ttctgggtga gcaaaaacag gaaggcaaaa tgccgcaaaa aagggaataa gggcgacacg 2280gaaatgttga atactcatac tcttcctttt tcaatattat tgaagcattt atcagggtta 2340ttgtctcatg agcggataca tatttgaatg tatttagaaa aataaacaaa taggggttcc 2400gcgcacattt ccccgaaaag tgccacctga cgtctaagaa accattatta tcatgacatt 2460aacctataaa aataggcgta tcacgaggcc ctttcgtctc gcgcgtttcg gtgatgacgg 2520tgaaaacctc tgacacatgc agctcccgga gacggtcaca gcttgtctgt aagcggatgc 2580cgggagcaga caagcccgtc agggcgcgtc agcgggtgtt ggcgggtgtc ggggctggct 2640taactatgcg gcatcagagc agattgtact gagagcgcac catatgcggt gtgaaatacc 2700gcacagatgc gtaaggagaa aataccgcat caggcgccat tcgccattca ggctgcgcaa 2760ctgttgggaa gggcgatcgg tgcgggcctc ttcgctatta cgccagctgg cgaaaggggg 2820atgtgctgca aggcgattaa gttgggtaac gccagggttt tcccagtcac gacgttgtaa 2880aacgacggcc agtgccaagc tagcggccgc cacgagtcta gctagagtac gaattcgagc 2940tcggaacccc tatacattga atcaatattg gcaattagcc atattagtca ttggttatat 3000agcataaatc aatattggct attggccatt gcatacgttg tatctatatc ataatatgta 3060catttatatt ggctcatgtc caatatgacc gccatgttga cattgattat tgactagtta 3120ttaatagtaa tcaattacgg ggtcattagt tcatagccca tatatggagt tccgcgttac 3180ataacttacg gtaaatggcc cgcctggctg accgcccaac gacccccgcc cattgacgtc 3240aataatgacg tatgttccca tagtaacgcc aatagggact ttccattgac gtcaatgggt 3300ggagtattta cggtaaactg cccacttggc agtacatcaa gtgtatcata tgccaagtcc 3360gccccctatt gacgtcaatg acggtaaatg gcccgcctgg cattatgccc agtacatgac 3420cttacgggac tttcctactt ggcagtacat ctacgtatta gtcatcgcta ttaccatggt 3480gatgcggttt tggcagtaca ccaatgggcg tggatagcgg tttgactcac ggggatttcc 3540aagtctccac cccattgacg tcaatgggag tttgttttgg caccaaaatc aacgggactt 3600tccaaaatgt cgtaataacc ccgccccgtt gacgcaaatg ggcggtaggc gtgtacggtg 3660ggaggtctat ataagcagag ctcgtttagt gaaccgtcag atcggggatc cgatatccac 3720catgggggag ccaggccagt cccctagtcc caggtcctcc catggcagtc ccccaactct 3780aagcactctc actctcctgc tgctcctctg tggacatgct cattctcaat gcaagatcct 3840ccgctgcaat gctgagtacg tatcgtccac tctgagcctt agaggtgggg gttcatcagg 3900agcacttcga ggaggaggag gaggaggccg gggtggaggg gtgggctctg gcggcctctg 3960tcgagccctc cgctcctatg cgctctgcac tcggcgcacc gcccgcacct gccgcgggga 4020cctcgccttc cattcggcgg tacatggcat cgaagacctg atgatccagc acaactgctc 4080ccgccagggc cctacagccc ctcccccgcc ccggggcccc gcccttccag gcgcgggctc 4140cggcctccct gccccggacc cttgtgacta tgaaggccgg ttttcccggc tgcatggtcg 4200tcccccgggg ttcttgcatt gcgcttcctt cggggacccc catgtgcgca gcttccacca 4260tcactttcac acatgccgtg tccaaggagc ttggcctcta ctggataatg acttcctctt 4320tgtccaagcc accagctccc ccatggcgtt gggggccaac gctaccgcca cccggaagct 4380caccatcata tttaagaaca tgcaggaatg cattgatcag aaggtgtatc aggctgaggt 4440ggataatctt cctgtagcct ttgaagatgg ttctatcaat ggaggtgacc gacctggggg 4500atccagtttg tcgattcaaa ctgctaaccc tgggaaccat gtggagatcc aagctgccta 4560cattggcaca actataatca ttcggcagac agctgggcag ctctccttct ccatcaaggt 4620agcagaggat gtggccatgg ccttctcagc tgaacaggac ctgcagctct gtgttggggg 4680gtgccctcca agtcagcgac tctctcgatc agagcgcaat cgtcggggag ctataaccat 4740tgatactgcc agacggctgt gcaaggaagg gcttccagtg gaagatgctt acttccattc 4800ctgtgtcttt gatgttttaa tttctggtga tcccaacttt accgtggcag ctcaggcagc 4860actggaggat gcccgagcct tcctgccaga cttagagaag ctgcatctct tcccctcagg 4920tggtggtggt ggtgatccca aatcttgtga caaacctcac acatgcccac tgtgcccagc 4980acctgaactc ctggggggac cgtcagtctt cctcttcccc ccaaaaccca aggacaccct 5040catgatctcc cggacccctg aggtcacatg cgtggtggtg gacgtgagcc acgaagaccc 5100tgaggtcaag ttcaactggt acgtggacgg cgtggaggtg cataatgcca agacaaagcc 5160gcgggaggag cagtacaaca gcacgtaccg tgtggtcagc gtcctcaccg tcctgcacca 5220ggactggctg aatggcaagg agtacaagtg caaggtctcc aacaaagccc tcccagcccc 5280catcgagaaa accatctcca aagccaaagg gcagccccga gaaccacagg tgtacaccct 5340gcccccatcc cgggatgagc tgaccaagaa ccaggtcagc ctgacctgcc tagtcaaagg 5400cttctatccc agcgacatcg ccgtggagtg ggagagcaat gggcagccgg agaacaacta 5460caaggccacg cctcccgtgc tggactccga cggctccttc ttcctctaca gcaagctcac 5520cgtggacaag agcaggtggc agcaggggaa cgtcttctca tgctccgtga tgcatgaggc 5580tctgcacaac cactacacgc agaagagcct ctccctgtct ccgggtaaat gagctgat 5638

Nucleic acids 14-250 of SEQ ID NO:11 form an SV40 polyadenosine. Nucleicacids 643-1297 form the origin of replication. Nucleic acids 1438-2413encode β-lacatamase. Nucleic acids 2932-3706 form a CMV promoter.Nucleic acids 3722-3826 encode the HJV leader. Nucleic acids 3827-4918encode human HJV. Nucleic acids 4919-4933 encode a glycine spacer.Nucleic acids 4934-5629 encode an IgG Fc. SEQ ID NO:11 is shownschematically in Figures

According to certain embodiments, the fusion protein of the presentdisclosure must form a dimer. In certain embodiments, the fusion proteinforms a dimer but does not form higher order aggregates such as 4 mers,6mers, 8mers, etc. These higher order associations can affect thesolubility of the fusion protein and its therapeutic effectiveness.

Definitions

Unless otherwise defined, scientific and technical terms used inconnection with the present disclosure shall have the meanings that arecommonly understood by those of ordinary skill in the art. Further,unless otherwise required by context, singular terms shall includepluralities and plural terms shall include the singular. Generally,nomenclatures utilized in connection with, and techniques of, cell andtissue culture, molecular biology, and protein and oligo- orpolynucleotide chemistry and hybridization described herein are thosewell known and commonly used in the art. Standard techniques are usedfor recombinant DNA, oligonucleotide synthesis, and tissue culture andtransformation (e.g., electroporation, lipofection). Enzymatic reactionsand purification techniques are performed according to manufacturer'sspecifications or as commonly accomplished in the art or as describedherein. The practice of compositions and methods described herein willemploy, unless indicated specifically to the contrary, conventionalmethods of virology, immunology, microbiology, molecular biology andrecombinant DNA techniques within the skill of the art, many of whichare described below for the purpose of illustration. Such techniques areexplained fully in the literature. See, e.g., Sambrook, et al. MolecularCloning: A Laboratory Manual (2nd Edition, 1989); Maniatis et al.Molecular Cloning: A Laboratory Manual (1982); DNA Cloning: A PracticalApproach, vol. I & II (D. Glover, ed.); Oligonucleotide Synthesis (N.Gait, ed., 1984); Nucleic Acid Hybridization (B. Hames & S. Higgins,eds., 1985); Transcription and Translation (B. Hames & S. Higgins, eds.,1984); Animal Cell Culture (R. Freshney, ed., 1986); Perbal, A PracticalGuide to Molecular Cloning (1984).

The nomenclatures utilized in connection with, and the laboratoryprocedures and techniques of, analytical chemistry, synthetic organicchemistry, and medicinal and pharmaceutical chemistry described hereinare those well known and commonly used in the art. Standard techniquesare used for chemical syntheses, chemical analyses, pharmaceuticalpreparation, formulation, and delivery, and treatment of patients.

The following definitions are useful in understanding the presentdisclosure:

A “mammal” for purposes of treating infection, refers to any mammal,including humans, domestic and farm animals, and zoo, sports, or petanimals, such as dogs, cats, cattle, horses, sheep, pigs, goats,rabbits, etc. Preferably, the mammal is human.

“Treating” or “treatment” or “alleviation” refers to both therapeutictreatment and prophylactic or preventative measures; wherein the objectis to prevent or slow down (lessen) the targeted pathologic condition ordisorder. Those in need of treatment include those already with thedisorder as well as those prone to have the disorder or those in whomthe disorder is to be prevented. A subject or mammal is successfully“treated” for an infection if, after receiving a therapeutic amount ofan antibody according to the methods of the present disclosure, thepatient shows observable and/or measurable reduction in or absence ofone or more of the following: reduction in the number of infected cellsor absence of the infected cells; reduction in the percent of totalcells that are infected; and/or relief to some extent, one or more ofthe symptoms associated with the specific infection; reduced morbidityand mortality, and improvement in quality of life issues. The aboveparameters for assessing successful treatment and improvement in thedisease are readily measurable by routine procedures familiar to aphysician.

The term “therapeutically effective amount” refers to an amount of acomposition effective to “treat” a disease or disorder in a subject ormammal. See preceding definition of “treating.”

“Chronic” administration refers to administration of the agent(s) in acontinuous mode as opposed to an acute mode, so as to maintain theinitial therapeutic effect (activity) for an extended period of time.“Intermittent” administration is treatment that is not consecutivelydone without interruption, but rather is cyclic in nature.

“Carriers” as used herein include pharmaceutically acceptable carriers,excipients, or stabilizers that are nontoxic to the cell or mammal beingexposed thereto at the dosages and concentrations employed. Often thephysiologically acceptable carrier is an aqueous pH buffered solution.Examples of physiologically acceptable carriers include buffers such asphosphate, citrate, and other organic acids; antioxidants includingascorbic acid; low molecular weight (less than about 10 residues)polypeptide; proteins, such as serum albumin, gelatin, orimmunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone;amino acids such as glycine, glutamine, asparagine, arginine or lysine;monosaccharides, disaccharides, and other carbohydrates includingglucose, mannose, or dextrins; chelating agents such as EDTA; sugaralcohols such as mannitol or sorbitol; salt-forming counterions such assodium; and/or nonionic surfactants such as TWEEN™ polyethylene glycol(PEG), and PLURONICS™.

The terms “nucleic acid” and “polynucleotide” are used interchangeablyherein to refer to single- or double-stranded RNA, DNA, PNA, or mixedpolymers. Polynucleotides may include genomic sequences, extra-genomicand plasmid sequences, and smaller engineered gene segments thatexpress, or may be adapted to express polypeptides.

An “isolated nucleic acid” is a nucleic acid that is substantiallyseparated from other genome DNA sequences as well as proteins orcomplexes such as ribosomes and polymerases, which naturally accompany anative sequence. The term embraces a nucleic acid sequence that has beenremoved from its naturally occurring environment, and includesrecombinant or cloned DNA isolates and chemically synthesized analoguesor analogues biologically synthesized by heterologous systems. Asubstantially pure nucleic acid includes isolated forms of the nucleicacid. Of course, this refers to the nucleic acid as originally isolatedand does not exclude genes or sequences later added to the isolatednucleic acid by the hand of man.

The term “polypeptide” is used in its conventional meaning, i.e., as asequence of amino acids. The polypeptides are not limited to a specificlength of the product. Peptides, oligopeptides, and proteins areincluded within the definition of polypeptide, and such terms may beused interchangeably herein unless specifically indicated otherwise.This term also does not refer to or exclude post-expressionmodifications of the polypeptide, for example, glycosylations,acetylations, phosphorylations and the like, as well as othermodifications known in the art, both naturally occurring andnon-naturally occurring. A polypeptide may be an entire protein, or asubsequence thereof. Particular polypeptides of interest in the contextof this disclosure are amino acid subsequences comprising CDRs and beingcapable of binding an antigen or Influenza A-infected cell.

An “isolated polypeptide” is one that has been identified and separatedand/or recovered from a component of its natural environment. Inpreferred embodiments, the isolated polypeptide will be purified (1) togreater than 95% by weight of polypeptide as determined by the Lowrymethod, and most preferably more than 99% by weight, (2) to a degreesufficient to obtain at least 15 residues of N-terminal or internalamino acid sequence by use of a spinning cup sequenator, or (3) tohomogeneity by SDS-PAGE under reducing or non-reducing conditions usingCoomassie blue or, preferably, silver stain. Isolated polypeptideincludes the polypeptide in situ within recombinant cells since at leastone component of the polypeptide's natural environment will not bepresent. Ordinarily, however, isolated polypeptide will be prepared byat least one purification step.

A “native sequence” polynucleotide is one that has the same nucleotidesequence as a polynucleotide derived from nature. A “native sequence”polypeptide is one that has the same amino acid sequence as apolypeptide (e.g., antibody) derived from nature (e.g., from anyspecies). Such native sequence polynucleotides and polypeptides can beisolated from nature or can be produced by recombinant or syntheticmeans.

A polynucleotide “variant,” as the term is used herein, is apolynucleotide that typically differs from a polynucleotide specificallydisclosed herein in one or more substitutions, deletions, additionsand/or insertions. Such variants may be naturally occurring or may besynthetically generated, for example, by modifying one or more of thepolynucleotide sequences of the present disclosure and evaluating one ormore biological activities of the encoded polypeptide as describedherein and/or using any of a number of techniques well known in the art.

A polypeptide “variant,” as the term is used herein, is a polypeptidethat typically differs from a polypeptide specifically disclosed hereinin one or more substitutions, deletions, additions and/or insertions.Such variants may be naturally occurring or may be syntheticallygenerated, for example, by modifying one or more of the abovepolypeptide sequences of the present disclosure and evaluating one ormore biological activities of the polypeptide as described herein and/orusing any of a number of techniques well known in the art.

Modifications may be made in the structure of the polynucleotides andpolypeptides of the present disclosure and still obtain a functionalmolecule that encodes a variant or derivative polypeptide with desirablecharacteristics. When it is desired to alter the amino acid sequence ofa polypeptide to create an equivalent, or even an improved, variant orportion of a polypeptide of the present disclosure, one skilled in theart will typically change one or more of the codons of the encoding DNAsequence.

For example, certain amino acids may be substituted for other aminoacids in a protein structure without appreciable loss of its ability tobind other polypeptides (e.g., antigens) or cells. Since it is thebinding capacity and nature of a protein that defines that protein'sbiological functional activity, certain amino acid sequencesubstitutions can be made in a protein sequence, and, of course, itsunderlying DNA coding sequence, and nevertheless obtain a protein withlike properties. It is thus contemplated that various changes may bemade in the peptide sequences of the disclosed compositions, orcorresponding DNA sequences that encode said peptides withoutappreciable loss of their biological utility or activity.

In many instances, a polypeptide variant will contain one or moreconservative substitutions. A “conservative substitution” is one inwhich an amino acid is substituted for another amino acid that hassimilar properties, such that one skilled in the art of peptidechemistry would expect the secondary structure and hydropathic nature ofthe polypeptide to be substantially unchanged.

It is known in the art that certain amino acids may be substituted byother amino acids having a similar hydropathic index or score and stillresult in a protein with similar biological activity, i.e. still obtaina biological functionally equivalent protein. In making such changes,the substitution of amino acids whose hydropathic indices are within ±2is preferred, those within ±1 are particularly preferred, and thosewithin ±0.5 are even more particularly preferred. It is also understoodin the art that the substitution of like amino acids can be madeeffectively on the basis of hydrophilicity. U.S. Pat. No. 4,554,101states that the greatest local average hydrophilicity of a protein, asgoverned by the hydrophilicity of its adjacent amino acids, correlateswith a biological property of the protein.

As outlined above, amino acid substitutions are generally thereforebased on the relative similarity of the amino acid side-chainsubstituents, for example, their hydrophobicity, hydrophilicity, charge,size, and the like. Exemplary substitutions that take one or more of theforegoing characteristics into consideration are well known to those ofskill in the art and include: arginine and lysine; glutamate andaspartate; serine and threonine; glutamine and asparagine; and valine,leucine and isoleucine.

Amino acid substitutions may further be made on the basis of similarityin polarity, charge, solubility, hydrophobicity, hydrophilicity and/orthe amphipathic nature of the residues. For example, negatively chargedamino acids include aspartic acid and glutamic acid; positively chargedamino acids include lysine and arginine; and amino acids with unchargedpolar head groups having similar hydrophilicity values include leucine,isoleucine and valine; glycine and alanine; asparagine and glutamine;and serine, threonine, phenylalanine and tyrosine. Other groups of aminoacids that may represent conservative changes include: (1) ala, pro,gly, glu, asp, gln, asn, ser, thr; (2) cys, ser, tyr, thr; (3) val, ile,leu, met, ala, phe; (4) lys, arg, his; and (5) phe, tyr, trp, his. Avariant may also, or alternatively, contain nonconservative changes. Ina preferred embodiment, variant polypeptides differ from a nativesequence by substitution, deletion or addition of five amino acids orfewer. Variants may also (or alternatively) be modified by, for example,the deletion or addition of amino acids that have minimal influence onthe immunogenicity, secondary structure and hydropathic nature of thepolypeptide.

Polypeptides may comprise a signal (or leader) sequence at theN-terminal end of the protein, which co-translationally orpost-translationally directs transfer of the protein. The polypeptidemay also be conjugated to a linker or other sequence for ease ofsynthesis, purification or identification of the polypeptide (e.g.,poly-His), or to enhance binding of the polypeptide to a solid support.For example, a polypeptide may be conjugated to an immunoglobulin Fcregion.

Optimal alignment of sequences for comparison may be conducted using theMegalign program in the Lasergene suite of bioinformatics software(DNASTAR, Inc., Madison, Wis.), using default parameters. This programembodies several alignment schemes described in the followingreferences: Dayhoff, M. O. (1978) A model of evolutionary change inproteins—Matrices for detecting distant relationships. In Dayhoff, M. O.(ed.) Atlas of Protein Sequence and Structure, National BiomedicalResearch Foundation, Washington D.C. Vol. 5, Suppl. 3, pp. 345-358; HeinJ. (1990) Unified Approach to Alignment and Phylogenes pp. 626-645Methods in Enzymology vol. 183, Academic Press, Inc., San Diego, Calif.;Higgins, D. G. and Sharp, P. M. (1989) CABIOS 5:151-153; Myers, E. W.and Muller W. (1988) CABIOS 4:11-17; Robinson, E. D. (1971) Comb. Theor11:105; Santou, N. Nes, M. (1987) Mol. Biol. Evol. 4:406-425; Sneath, P.H. A. and Sokal, R. R. (1973) Numerical Taxonomy—the Principles andPractice of Numerical Taxonomy, Freeman Press, San Francisco, Calif.;Wilbur, W. J. and Lipman, D. J. (1983) Proc. Natl. Acad., Sci. USA80:726-730.

Alternatively, optimal alignment of sequences for comparison may beconducted by the local identity algorithm of Smith and Waterman (1981)Add. APL. Math 2:482, by the identity alignment algorithm of Needlemanand Wunsch (1970) J. Mol. Biol. 48:443, by the search for similaritymethods of Pearson and Lipman (1988) Proc. Natl. Acad. Sci. USA 85:2444, by computerized implementations of these algorithms (GAP, BESTFIT,BLAST, FASTA, and TFASTA in the Wisconsin Genetics Software Package,Genetics Computer Group (GCG), 575 Science Dr., Madison, Wis.), or byinspection.

One preferred example of algorithms that are suitable for determiningpercent sequence identity and sequence similarity are the BLAST andBLAST 2.0 algorithms, which are described in Altschul et al. (1977)Nucl. Acids Res. 25:3389-3402 and Altschul et al. (1990) J. Mol. Biol.215:403-410, respectively. BLAST and BLAST 2.0 can be used, for examplewith the parameters described herein, to determine percent sequenceidentity for the polynucleotides and polypeptides of the presentdisclosure. Software for performing BLAST analyses is publicly availablethrough the National Center for Biotechnology Information.

“Homology” refers to the percentage of residues in the polynucleotide orpolypeptide sequence variant that are identical to the non-variantsequence after aligning the sequences and introducing gaps, ifnecessary, to achieve the maximum percent homology. In particularembodiments, polynucleotide and polypeptide variants have at least 70%,at least 75%, at least 80%, at least 90%, at least 95%, at least 98%, orat least 99% polynucleotide or polypeptide homology with apolynucleotide or polypeptide described herein.

“Vector” includes shuttle and expression vectors. Typically, the plasmidconstruct will also include an origin of replication (e.g., the ColE1origin of replication) and a selectable marker (e.g., ampicillin ortetracycline resistance), for replication and selection, respectively,of the plasmids in bacteria. An “expression vector” refers to a vectorthat contains the necessary control sequences or regulatory elements forexpression of the antibodies including antibody fragment of the presentdisclosure, in bacterial or eukaryotic cells. Suitable vectors aredisclosed below.

The term “variant” refers to a protein or polypeptide in which one ormore amino acid substitutions, deletions, and/or insertions are presentas compared to the amino acid sequence of an protein or peptide andincludes naturally occurring allelic variants or alternative splicevariants of an protein or peptide. The term “variant” includes thereplacement of one or more amino acids in a peptide sequence with asimilar or homologous amino acid(s) or a dissimilar amino acid(s).Preferred variants include alanine substitutions at one or more of aminoacid positions. Other preferred substitutions include conservativesubstitutions that have little or no effect on the overall net charge,polarity, or hydrophobicity of the protein. Conservative substitutionsare set forth above.

Other variants can consist of less conservative amino acidsubstitutions, such as selecting residues that differ more significantlyin their effect on maintaining (a) the structure of the polypeptidebackbone in the area of the substitution, for example, as a sheet orhelical conformation, (b) the charge or hydrophobicity of the moleculeat the target site, or (c) the bulk of the side chain. The substitutionsthat in general are expected to have a more significant effect onfunction are those in which (a) glycine and/or proline is substituted byanother amino acid or is deleted or inserted; (b) a hydrophilic residue,e.g., seryl or threonyl, is substituted for (or by) a hydrophobicresidue, e.g., leucyl, isoleucyl, phenylalanyl, valyl, or alanyl; (c) acysteine residue is substituted for (or by) any other residue; (d) aresidue having an electropositive side chain, e.g., lysyl, arginyl, orhistidyl, is substituted for (or by) a residue having an electronegativecharge, e.g., glutamyl or aspartyl; or (e) a residue having a bulky sidechain, e.g., phenylalanine, is substituted for (or by) one not havingsuch a side chain, e.g., glycine. Other variants include those designedto either generate a novel glycosylation and/or phosphorylation site(s),or those designed to delete an existing glycosylation and/orphosphorylation site(s). Variants include at least one amino acidsubstitution at a glycosylation site, a proteolytic cleavage site and/ora cysteine residue. Variants also include proteins and peptides withadditional amino acid residues before or after the protein or peptideamino acid sequence on linker peptides. The term “variant” alsoencompasses polypeptides that have the amino acid sequence of theproteins/peptides of the present disclosure with at least one and up to25 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20) additional amino acidsflanking either the 3′ or 5′ end of the amino acid sequence or both.

The term “variant” also refers to a protein that is at least 60 to 99percent identical (e.g., 60, 65, 70, 75, 80, 85, 90, 95, 98, 99, or100%, inclusive) in its amino acid sequence of the proteins of thepresent disclosure as determined by standard methods that are commonlyused to compare the similarity in position of the amino acids of twopolypeptides. The degree of similarity or identity between two proteinscan be readily calculated by known methods. Preferred methods todetermine identity are designed to give the largest match between thesequences tested. Methods to determine identity and similarity arecodified in publicly available computer programs. Variants willtypically have one or more (e.g., 2, 3, 4, 5, etc.) amino acidsubstitutions, deletions, and/or insertions as compared with thecomparison protein or peptide, as the case may be.

A “mature” form of a fusion protein disclosed in the present disclosureis the product of a naturally occurring polypeptide or precursor form orproprotein. The naturally occurring polypeptide, precursor or proproteinincludes, by way of nonlimiting example, the full length gene productencoded by the corresponding gene. Alternatively, it may be defined asthe polypeptide, precursor or proprotein encoded by an open readingframe described herein. The product “mature” form arises, by way ofnonlimiting example, as a result of one or more naturally occurringprocessing steps that may take place within the cell (e.g., host cell)in which the gene product arises. Examples of such processing stepsleading to a “mature” form of a polypeptide or protein include thecleavage of the N terminal methionine residue encoded by the initiationcodon of an ORF, or the proteolytic cleavage of a signal peptide orleader sequence. Further as used herein, a “mature” form of apolypeptide or protein may arise from a step of post translationalmodification other than a proteolytic cleavage event. Such additionalprocesses include, by way of non limiting example, glycosylation,myristylation or phosphorylation. In general, a mature polypeptide orprotein may result from the operation of only one of these processes, ora combination of any of them.

The term “derivative” refers to a chemically modified protein orpolypeptide that has been chemically modified either by naturalprocesses, such as processing and other post-translationalmodifications, but also by chemical modification techniques, as forexample, by addition of one or more polyethylene glycol molecules,sugars, phosphates, and/or other such molecules, where the molecule ormolecules are not naturally attached to wild-type proteins. Derivativesinclude salts. Such chemical modifications are well described in basictexts and in more detailed monographs, as well as in a voluminousresearch literature, and they are well known to those of skill in theart. It will be appreciated that the same type of modification may bepresent in the same or varying degree at several sites in a givenprotein or polypeptide. Also, a given protein or polypeptide may containmany types of modifications. Modifications can occur anywhere in aprotein or polypeptide, including the peptide backbone, the amino acidside-chains, and the amino or carboxyl termini. Modifications include,for example, acetylation, acylation, ADP-ribosylation, amidation,covalent attachment of flavin, covalent attachment of a heme moiety,covalent attachment of a nucleotide or nucleotide derivative, covalentattachment of a lipid or lipid derivative, covalent attachment ofphosphotidylinositol, cross-linking, cyclization, disulfide bondformation, demethylation, formation of covalent cross-links, formationof cysteine, formation of pyroglutamate, formylation,gamma-carboxylation, glycosylation, GPI anchor formation, hydroxylation,iodination, methylation, myristoylation, oxidation, proteolyticprocessing, phosphorylation, prenylation, racemization, glycosylation,lipid attachment, sulfation, gamma-carboxylation of glutamic acidresidues, hydroxylation and ADP-ribosylation, selenoylation, sulfation,transfer-RNA mediated addition of amino acids to proteins, such asarginylation, and ubiquitination.

The term “derivatives” include chemical modifications resulting in theprotein or polypeptide becoming branched or cyclic, with or withoutbranching. Cyclic, branched and branched circular proteins orpolypeptides may result from post-translational natural processes andmay be made by entirely synthetic methods, as well. Examples of suchderivatives include (i) N-acyl derivatives of the amino terminal or ofanother free amino group, wherein the acyl group may be an alkanoylgroup (e.g., acetyl, hexanoyl, octanoyl), an aroyl group (e.g., benzoyl)or a blocking group such as F-moc (fluorenylmethyl-O—CO—); (ii) estersof the carboxy terminal or of another free carboxy or hydroxyl group;(iii) amide of the carboxy terminus or of another free carboxyl groupproduced by reaction with ammonia or with a suitable amine; (iv)phosphorylated derivatives; (v) derivatives conjugated to an antibody orother biological ligand and other types of derivatives.

The term “derivatives” include chemical modifications resulting in theprotein or polypeptide becoming branched or cyclic, with or withoutbranching. Cyclic, branched and branched circular proteins orpolypeptides may result from post-translational natural processes andmay be made by entirely synthetic methods, as well. A cyclic derivativecontaining an intramolecular disulfide bond may be prepared byconventional solid phase synthesis while incorporating suitableS-protected cysteine or homocysteine residues at the positions selectedfor cyclization such as the amino and carboxy termini Followingcompletion of the chain assembly, cyclization can be performed either(1) by selective removal of the S-protecting group with a consequenton-support oxidation of the corresponding two free SH-functions, to forma S—S bonds, followed by conventional removal of the product from thesupport and appropriate purification procedure; or (2) by removal of thepeptide from the support along with complete side chain deprotection,followed by oxidation of the free SH-functions in highly dilute aqueoussolution.

The cyclic derivative containing an intramolecular amide bond may beprepared by conventional solid phase synthesis while incorporatingsuitable amino and carboxyl side chain protected amino acid derivatives,at the position selected for cyclization. The cyclic derivativescontaining intramolecular —S— alkyl bonds can be prepared byconventional solid phases while incorporating an amino acid residue witha suitable amino-protected side chain, and a suitable S-protectedcysteine or homocysteine residue at the position selected forcyclization.

Systematic substitution of one or more amino acids of a consensussequence with D-amino acid of the same type (e.g., D-lysine in place ofL-lysine) may be used to generate more stable peptides. Thus, a peptidederivative or peptidomimetic of the present disclosure may be all L, allD or mixed D, L peptide. In a preferred embodiment, the peptides consistof all D-amino acids. The presence of an N-terminal or C-terminalD-amino acid increases the in vivo stability of a peptide sincepeptidases cannot utilize a D-amino acid as a substrate.

Substitution of unnatural amino acids for natural amino acids in asubsequence of the peptides can also confer resistance to proteolysis.Such a substitution can, for instance, confer resistance to proteolysisby exopeptidases acting on the N-terminus. Such substitutions have beendescribed and these substitutions do not affect biological activity.Examples of non-naturally occurring amino acids includeα,α-disubstituted amino acids, N-alkyl amino acids, lactic acids,C-α-methyl amino acids, and β-methyl amino acids Amino acid analogsuseful in the present disclosure may include but are not limited toβ-alanine, norvaline, norleucine, 4-aminobutyric acid, orithine,hydroxyproline, sarcosine, citrulline, cysteic acid, cyclohexylalanine,2-aminoisobutyric acid, 6-aminohexanoic acid, t-butylglycine,phenylglycine, o-phosphoserine, N-acetyl serine, N-formylmethionine,3-methylhistidine and other unconventional amino acids. Furthermore, thesynthesis of peptides with unnatural amino acids is routine and known inthe art.

One other effective approach to confer resistance to peptidases actingon the N-terminal or C-terminal residues of a peptide is to add chemicalgroups at the peptide termini, such that the modified peptide is nolonger a substrate for the peptidase. One such chemical modification isglycosylation of the peptides at either or both termini Certain chemicalmodifications, in particular N-terminal glycosylation, have been shownto increase the stability of peptides in human serum. Other chemicalmodifications which enhance serum stability include, but are not limitedto, the addition of an N-terminal alkyl group, consisting of a loweralkyl of from 1 to 20 carbons, such as an acetyl group, and/or theaddition of a C-terminal amide or substituted amide group. In particularthe present disclosure includes modified peptides consisting of peptidesbearing an N-terminal acetyl group and/or a C-terminal amide group.

The term “peptide mimetic” or “mimetic” refers to biologically activecompounds that mimic the biological activity of a peptide or a proteinbut are no longer peptidic in chemical nature, that is, they no longercontain any peptide bonds (that is, amide bonds between amino acids).Here, the term peptide mimetic is used in a broader sense to includemolecules that are no longer completely peptidic in nature, such aspseudo-peptides, semi-peptides and peptoids. Examples of peptidemimetics in this broader sense (where part of a peptide is replaced by astructure lacking peptide bonds) are described below. Whether completelyor partially non-peptide, peptide mimetics according to the embodimentsprovide a spatial arrangement of reactive chemical moieties that closelyresemble the three-dimensional arrangement of active groups in thepeptide on which the peptide mimetic is based. As a result of thissimilar active-site geometry, the peptide mimetic has effects onbiological systems that are similar to the biological activity of thepeptide.

Peptide mimetics include reverse-D peptides which contain D-amino acidsarranged in a reverse sequence relative to a peptide containing L-aminoacids. For example, the C-terminal residue of an L-amino acid peptidebecomes N-terminal for the D-amino acid peptide, and so forth. ReverseD-peptides desirably retain the same tertiary conformation and thereforethe same activity, as the L-amino acid peptides, but desirably are morestable to enzymatic degradation in vitro and in vivo, and therefore canhave greater therapeutic efficacy than the original peptide (Brady andDodson, Nature 368:692-693, 1994; and Jameson and McDonnel, Nature368:744-746, 1994). Peptide mimetics also include reverse-L peptideswhich contain L-amino acids arranged in a reverse sequence relative to aparent peptide. The C-terminal residue of the parent peptide becomesN-terminal for the reverse-L peptide, and so forth.

The peptide mimetics of the embodiments are preferably substantiallysimilar in both three-dimensional shape and biological activity to thepeptides described herein. Examples of methods of structurally modifyinga peptide known in the art to create a peptide mimetic include theinversion of backbone chiral centers leading to D-amino acid residuestructures that may, particularly at the N-terminus, lead to enhancedstability for proteolytic degradation without adversely affectingactivity. A second method is altering cyclic structure for stability,such as N to C interchain imides and lactams. An example of this isgiven in conformationally restricted thymopentin-like compounds, such asthose disclosed in U.S. Pat. No. 4,457,489, the present disclosure ofwhich is incorporated by reference herein in its entirety. A thirdmethod is to substitute peptide bonds in the peptide by pseudopeptidebonds that confer resistance to proteolysis.

A peptide mimetics may include protective groups at one or both ends ofthe mimetic, or replacement of one or more peptide bonds withnon-peptide bonds, is less susceptible to proteolytic cleavage than thepeptide itself. For instance, one or more peptide bonds can be replacedwith an alternative type of covalent bond (e.g., a carbon-carbon bond oran acyl bond). Peptide mimetics can also incorporate amino-terminal orcarboxyl terminal blocking groups such as t-butyloxycarbonyl, acetyl,alkyl, succinyl, methoxysuccinyl, suberyl, adipyl, azelayl, dansyl,benzyloxycarbonyl, fluorenylmethoxycarbonyl, methoxyazelayl,methoxyadipyl, methoxysuberyl, and 2,4,-dinitrophenyl, thereby renderingthe mimetic less susceptible to proteolysis. Non-peptide bonds andcarboxyl- or amino-terminal blocking groups can be used singly or incombination to render the mimetic less susceptible to proteolysis thanthe corresponding peptide. Additionally, substitution of D-amino acidsfor the normal L-stereoisomer can be effected, e.g. to increase thehalf-life of the molecule. Accordingly, the peptide mimetics includepeptides having one or more of the following modifications: peptideswherein one or more of the peptidyl [—C(O)NR—] linkages (bonds) havebeen replaced by a non-peptidyl linkage such as a —CH₂-carbamate linkage[—CH₂—OC(O)NR—]; a phosphonate linkage; a —CH₂-sulfonamide[—CH₂—S(O)₂NR—] linkage; a urea [—NHC(O)NH—] linkage; a —CH₂-secondaryamine linkage; or an alkylated peptidyl linkage [—C(O)NR⁶— where R⁶ islower alkyl]; peptides wherein the N-terminus is derivatized to a —NRR¹group; to a —NRC(O)R group; to a —NRC(O)OR group; to a —NRS(O)₂R group;to a —NHC(O)NHR group, where R and R¹ are hydrogen or lower alkyl withthe proviso that R and R¹ are not both hydrogen; to a succinimide group;to a benzyloxycarbonyl-NH—(CBZ—CH—) group; or to a benzyloxycarbonyl-NE-group having from 1 to 3 substituents on the phenyl ring selected fromthe group consisting of lower alkyl, lower alkoxy, chloro, and bromo; orpeptides wherein the C terminus is derivatized to —C(O)R² where R² isselected from the group consisting of lower alkoxy, and —NR³R⁴ where R³and R⁴ are independently selected from the group consisting of hydrogenand lower alkyl.

Preferred mimetics have from zero to all of the —C(O)NH— linkages of thepeptide replaced by a linkage selected from the group consisting of a—CR₂OC(O)NR—linkage; a phosphonate linkage; a —CH₂S(O)₂NR— linkage; a—CH₂NR— linkage; and a —C(O)NR⁶— linkage, and a —NHC(O)NH— linkage whereR is hydrogen or lower alkyl and R⁶ is lower alkyl, and wherein theN-terminus of the mimetic is selected from the group consisting of a—NRR¹ group; a —NRC(O)R group; a —NRC(O)OR group; a —NRS(O)₂R group; a—NHC(O)NHR group; a succinimide group; a benzyloxycarbonyl-NH— group;and a benzyloxycarbonyl-NH— group having from 1 to 3 substituents on thephenyl ring selected from the group consisting of lower alkyl, loweralkoxy, chloro, and bromo, where R and R¹ are independently selectedfrom the group consisting of hydrogen and lower alkyl, and still furtherwherein the C-terminus of the mimetic has the formula —C(O)R² where R²is selected from the group consisting of hydroxy, lower alkoxy, and—NR³R⁴ where R³ and R⁴ are independently selected from the groupconsisting of hydrogen and lower alkyl and where the nitrogen atom ofthe —NR³R⁴ group can optionally be the amine group of the N-terminus ofthe peptide so as to form a cyclic peptide, and physiologicallyacceptable salts thereof.

The term “fragment” or “subsequence” refers to a protein or polypeptidethat consists of a continuous subsequence of the amino acid sequence ofa protein or peptide and includes naturally occurring fragments such assplice variants and fragments resulting from naturally occurring in vivoprotease activity. Such a fragment may be truncated at the aminoterminus, the carboxy terminus, and/or internally (such as by naturalsplicing). Such fragments may be prepared with or without an aminoterminal methionine. The term “fragment” includes fragments, whetheridentical or different, from the same protein or peptide, with acontiguous amino acid sequence in common or not, joined together, eitherdirectly or through a linker. Such fragments may comprise at least 3contiguous amino acids that are identical to the amino acid sequence ofthe present disclosure.

The phrase “pharmaceutically acceptable” or “therapeutically acceptable”refers to molecular entities and compositions that are physiologicallytolerable and preferably do not typically produce an allergic or similaruntoward reaction, such as gastric upset, dizziness and the like, whenadministered to a human. Preferably, as used herein, the term“pharmaceutically acceptable” means approved by a regulatory agency ofthe Federal or a State government or listed in the U.S. Pharmacopeia orother generally recognized pharmacopeia (e.g., Remington'sPharmaceutical Sciences) for use in animals, and more particularly inhumans.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one,” butit is also consistent with the meaning of “one or more,” “at least one,”and “one or more than one.”

Throughout this application, the term “about” is used to indicate that avalue includes the standard deviation of error for the device or methodbeing employed to determine the value.

Iron Metabolism Diseases

Conditions that may be treated and/or prevented using the fusionproteins or variants, derivatives, fragments or peptide mimetics derivedtherefrom of the present disclosure include any disease, disorder, orsyndrome associated with perturbations in iron metabolism. Perturbationsin iron metabolism may be associated with disturbances in one or more ofiron uptake, iron absorption, iron transport, iron storage, ironprocessing, iron mobilization, and iron utilization. Generally,perturbations in iron metabolism result in iron overload, ironmaldistribution or iron deficiency.

Conditions associated with iron overload include both primary andsecondary iron overload diseases, syndromes or disorders, including, butnot limited to, hereditary hemochromatosis, porphyria cutanea tarda,hereditary spherocytosis, hypochromic anemia, hypererythropoietic anemia(CDAI), faciogenital dysplasia (FGDY), Aarskog syndrome,atransferrinemia, sideroblastic anemia (SA), pyridoxine-responsivesideroblastic anemia, and hemoglobinopathies such as thalassemia andsickle cell. Some studies have suggested an association between ironmetabolism disorders, such as thalassemia and hemochromatosis, and anumber of disease states, such as type II (non-insulin dependent)diabetes mellitus and atherosclerosis (A. J. Matthews et al., J. Surg.Res., 1997, 73: 3540; T. P. Tuomainen et al., Diabetes Care, 1997, 20:426-428).

Diseases associated with iron deficiency and/or iron maldistributioninclude, but are not limited to, anemia of chronic disease, anemia ofinflammation, iron deficiency anemias, functional iron deficiency, andmicrocytic anemia. The terms “anemia of chronic disease” or “anemia ofinflammation” refer to any anemia that develops as a result of, forexample, extended infection, inflammation, neoplastic disorders, etc.The anemia which develops is often characterized by a shortened redblood cell life span and sequestration of iron in macrophages, whichresults in a decrease in the amount of iron available to make new redblood cells. Conditions associated with anemia of chronic disease oranemia of inflammation include, but are not limited to, chronic kidneydisease, end stage renal disease, neoplastic disorders, chronicbacterial endocarditis, osteomyelitis, rheumatic fever, and ulcerativecolitis. Further conditions include other diseases and disordersassociated with infection, inflammation, and neoplasms, including, forexample, inflammatory infections (e.g., pulmonary abscess, tuberculosis,etc), inflammatory noninfectious disorders (e.g., rheumatoid arthritis,systemic lupus erythrematosus, Crohn's disease, hepatitis, inflammatorybowel disease, etc.), and various cancers, tumors, and malignancies(e.g., carcinoma, sarcoma, lymphoma, etc.). Iron deficiency anemia mayresult from conditions such as pregnancy, menstruation, infancy andchildhood, blood loss due to injury, etc.

It has also been suggested that iron metabolism plays a role in a numberof other diseases states, including cardiovascular disease (e.g.congestive heart failure), Alzheimer's disease, Parkinson's disease, andcertain types of colorectal cancers (see, for example, P. Tuomainen etal., Circulation, 1997, 97: 1461-1466; J. M. McCord, Circulation, 1991,83: 1112-1114; J. L. Sullivan, J. Clin. Epidemiol., 1996, 49: 1345-1352;M. A. Smith et al., Proc. Nat. Acad. Sci., 1997, 94: 9866-9868; P.Riederer et al., J. Neurochem., 1989, 512: 515-520; P. Knekt et al.,Int. J. Cancer, 1994, 56: 379-382).

Cancer

It has been shown that gene expression profiles in breast cancersfrom >800 women reveal that decreased ferroportin gene expression isassociated with a significant reduction in metastasis-free anddisease-specific survival that is independent of other breast cancerrisk factors. (Pinnix et al. Science Translational Medicine 2(43):1-10(August 2010)). High ferroportin and low hepcidin gene expressionidentified an extremely favorable cohort of breast cancer patients whohave a 10-year survival of >90%. Thus, administering HJV.Fc to lower BMPsignaling and thus hepcidin gene expression and to elevate ferroportinlevels in cancer patients, including but not limited to breast cancerpatients, should achieve a significant reduction in metastasis-free anddisease-specific survival.

Pharmaceutical Compositions

The present disclosure relates to a method for therapy, prevention andamelioration of iron homeostasis disorders. The fusion proteins andvariants, derivatives, fragments and peptide mimetics derived therefromof the present disclosure are useful in the treatment of conditions ordiseases associated with iron homeostasis.

Therefore, methods of the present disclosure comprise administering to asubject in need thereof or at risk of being in need thereof an effectiveamount of one or more of the fusion proteins or variants, derivatives,fragments and peptide mimetics derived therefrom of the presentdisclosure, or a composition comprising one or more of the fusionproteins or variants, derivatives, fragments and peptide mimeticsderived therefrom of the present disclosure to a subject, to mobilizeiron and increase serum hemoglobin and/or hematocrit levels. In oneembodiment, an effective amount of a therapeutic composition comprisingone or more of the fusion proteins or variants, derivatives, fragmentsand peptide mimetics derived therefrom of the present disclosure and asuitable pharmaceutical carrier is administered to a subject to mobilizeiron and increase serum hemoglobin and/or hematocrit levels to preventor ameliorate symptoms or treat a disorder, disease or condition relatedto iron homeostasis. In one embodiment, the subject is an animal. Inanother embodiment, the subject is a mammal, and preferably a human.

The fusion proteins or variants, derivatives, fragments and peptidemimetics derived therefrom of the present disclosure are used in thetreatment, prophylaxis or amelioration of symptoms in any diseasecondition or disorder where the mobilization of iron and increase inserum hemoglobin and/or hematocrit levels might be beneficial.

Compositions within the scope of the present disclosure should containthe active agent (e.g. one or more of the fusion proteins or variants,derivatives, fragments and peptide mimetics derived therefrom of thepresent disclosure) in an amount effective to achieve the desiredtherapeutic effect while avoiding adverse side effects. Pharmaceuticallyacceptable preparations and salts of the active agent are within thescope of the present disclosure and are well known in the art. For theadministration of polypeptide antagonists and the like, the amountadministered should be chosen so as to avoid adverse side effects. Theamount of the therapeutic or pharmaceutical composition which iseffective in the treatment of a particular disease, disorder orcondition will depend on the nature and severity of the disease, thetarget site of action, the patient's weight, special diets beingfollowed by the patient, concurrent medications being used, theadministration route and other factors that will be recognized by thoseskilled in the art. The dosage will be adapted by the clinician inaccordance with conventional factors such as the extent of the diseaseand different parameters from the patient. Typically, 0.001 to 100 mg/kgare administered to the subject twice a week. Preferably, 10 to 30 mg/kgare administered to the subject twice a week. In one specificembodiment, 20 mg/kg are administered to the subject twice a week.Effective doses may be extrapolated from dose response curves derivedfrom in vitro or animal model test systems. For example, in order toobtain an effective mg/kg dose for humans based on data generated fromrat studies, the effective mg/kg dosage in rat is divided by six.

Various delivery systems are known and can be used to administer thefusion proteins or variants, derivatives, fragments and peptide mimeticsderived therefrom or a pharmaceutical composition containing thesefusion proteins or variants, derivatives, fragments and peptide mimeticsderived therefrom of the present disclosure. The pharmaceuticalcomposition of the present disclosure can be administered by anysuitable route including, intravenous or intramuscular injection,intraventricular or intrathecal injection (for central nervous systemadministration), orally, topically, subcutaneously, subconjunctivally,or via intranasal, intradermal, sublingual, vaginal, rectal or epiduralroutes. The preferred route of administration is intravenousadministration.

Other delivery systems well known in the art can be used for delivery ofthe pharmaceutical compositions of the present disclosure, for examplevia aqueous solutions, encapsulation in microparticles, ormicrocapsules.

In yet another embodiment, the pharmaceutical compositions of thepresent disclosure can be delivered in a controlled release system. Inone embodiment polymeric materials can be used, in another embodiment, apump may be used.

As mentioned above, pharmaceutical compositions of the presentdisclosure comprise one or more of the fusion proteins or variants,derivatives, fragments and peptide mimetics derived therefrom of thepresent disclosure combined with a pharmaceutically acceptable carrier.The term carrier refers to diluents, adjuvants and/or excipients such asfillers, binders, disintegrating agents, lubricants, silica flowconditioner, stabilizing agents or vehicles with which the peptide,peptide derivative or peptidomimetic is administered. Suchpharmaceutical carriers include sterile liquids such as water and oilsincluding mineral oil, vegetable oil (e.g., peanut oil, soybean oil,sesame oil and canola oil), animal oil or oil of synthetic origin.Aqueous glycerol and dextrose solutions as well as saline solutions mayalso be employed as liquid carriers of the pharmaceutical compositionsof the present disclosure. Of course, the choice of the carrier dependson the nature of the peptide, peptide derivative or peptidomimetic, itssolubility and other physiological properties as well as the target siteof delivery and application. Examples of suitable pharmaceuticalcarriers are described in Remington: The Science and Practice ofPharmacy by Alfonso R. Gennaro, 2003, 21st edition, Mack PublishingCompany.

Further pharmaceutically suitable materials that may be incorporated inpharmaceutical preparations of the present disclosure include absorptionenhancers, pH regulators and buffers, osmolarity adjusters,preservatives, stabilizers, antioxidants, surfactants, thickeners,emollient, dispersing agents, flavoring agents, coloring agents andwetting agents.

Examples of suitable pharmaceutical excipients include, water, glucose,sucrose, lactose, glycol, ethanol, glycerol monostearate, gelatin, rice,starch, flour, chalk, sodium stearate, malt, sodium chloride and thelike. The pharmaceutical compositions of the present disclosure can takethe form of solutions, capsules, tablets, creams, gels, powders,sustained release formulations and the like. The composition can beformulated as a suppository, with traditional binders and carriers suchas triglycerides (see Remington: The Science and Practice of Pharmacy byAlfonso R. Gennaro, 2003, 21.sup.th edition, Mack Publishing Company).Such compositions contain a therapeutically effective amount of thetherapeutic composition, together with a suitable amount of carrier soas to provide the form for proper administration to the subject. Theformulations are designed so as to suit the mode of administration andthe target site of action (e.g., a particular organ or cell type).

The pharmaceutical compositions of the present disclosure can beformulated as neutral or salt forms. Pharmaceutically acceptable saltsinclude those that form with free amino groups and those that react withfree carboxyl groups. Non-toxic alkali metal, alkaline earth metal andammonium salts commonly used in the pharmaceutical industry includesodium, potassium, lithium, calcium, magnesium, barium, ammonium, andprotamine zinc salts, which are prepared by methods well known in theart. The term also includes non-toxic acid addition salts, which aregenerally prepared by reacting the compounds of the present disclosurewith suitable organic or inorganic acid. Representative salts includethe hydrobromide, hydrochloride, valerate, oxalate, oleate, laureate,borate, benzoate, sulfate, bisulfate, acetate, phosphate, tysolate,citrate, maleate, fumarate, tartrate, succinate, napsylate salts and thelike.

Examples of fillers or binders that may be used in accordance with thepresent disclosure include acacia, alginic acid, calcium phosphate(dibasic), carboxymethylcellulose, carboxymethylcellulose sodium,hydroxyethylcellulose, hydroxypropylcellulose,hydroxypropylmethylcellulose, dextrin, dextrates, sucrose, tylose,pregelatinized starch, calcium sulfate, amylose, glycine, bentonite,maltose, sorbitol, ethylcellulose, disodium hydrogen phosphate, disodiumphosphate, disodium pyrosulfite, polyvinyl alcohol, gelatin, glucose,guar gum, liquid glucose, compressible sugar, magnesium aluminumsilicate, maltodextrin, polyethylene oxide, polymethacrylates, povidone,sodium alginate, tragacanth, microcrystalline cellulose, starch, andzein. Another most preferred filler or binder consists ofmicrocrystalline cellulose.

Examples of disintegrating agents that may be used include alginic acid,carboxymethylcellulose, carboxymethylcellulose sodium,hydroxypropylcellulose (low substituted), microcrystalline cellulose,powdered cellulose, colloidal silicon dioxide, sodium croscarmellose,crospovidone, methylcellulose, polacrilin potassium, povidone, sodiumalginate, sodium starch glycolate, starch, disodium disulfite, disodiumedathamil, disodium edetate, disodiumethylenediaminetetraacetate (EDTA)crosslinked polyvinylpyrollidines, pregelatinized starch, carboxymethylstarch, sodium carboxymethyl starch and microcrystalline cellulose.

Examples of lubricants include calcium stearate, canola oil, glycerylpalmitostearate, hydrogenated vegetable oil (type I), magnesium oxide,magnesium stearate, mineral oil, poloxamer, polyethylene glycol, sodiumlauryl sulfate, sodium stearate fumarate, stearic acid, talc, zincstearate, glyceryl behapate, magnesium lauryl sulfate, boric acid,sodium benzoate, sodium acetate, sodium benzoate/sodium acetate (incombination) and DL leucine.

Examples of silica flow conditioners include colloidal silicon dioxide,magnesium aluminum silicate and guar gum. Another most preferred silicaflow conditioner consists of silicon dioxide.

Examples of stabilizing agents include acacia, albumin, polyvinylalcohol, alginic acid, bentonite, dicalcium phosphate,carboxymethylcellulose, hydroxypropylcellulose, colloidal silicondioxide, cyclodextrins, glyceryl monostearate, hydroxypropylmethylcellulose, magnesium trisilicate, magnesium aluminum silicate,propylene glycol, propylene glycol alginate, sodium alginate, carnaubawax, xanthan gum, starch, stearate(s), stearic acid, stearicmonoglyceride and stearyl alcohol.

The present disclosure also provides for modifications of peptides orpeptide derivatives such that they are more stable once administered toa subject (i.e., once administered it has a longer half-life or longerperiod of effectiveness as compared to the unmodified form). Suchmodifications are well known to those skilled in the art to which thisdisclosure pertain (e.g., polyethylene glycol derivatization a.k.a.PEGylation, microencapsulation, etc.).

Methods of Screening

The present disclosure provides for methods of screening for compounds(e.g., HJV-IgG fusion proteins and variants, derivatives and peptidemimetics derived therefrom.) that alter serum iron, serum hemoglobinand/or hematocrit levels in mammalian subjects. According to someembodiments, there is provided a method for screening for compounds thatmobilize iron and serum hemoglobin and/or hematocrit levels in mammaliansubjects (e.g., increased or decreased).

In another embodiment, the present disclosure provides methods ofscreening for compounds, wherein the compounds are screened for theirability to specifically bind to BMP-6. In specific embodiments,compositions of the present disclosure are screened for their ability ofbind to BMP-6 with a K_(D) of at least 10⁻⁵, 10⁻⁶, 10⁻⁷, 10⁻⁸, 10⁻⁹,10^(×10), 10⁻¹¹ or 10⁻¹² M. In another embodiment, the presentdisclosure provides methods of screening for compounds, wherein thecompounds are screened for their ability to inhibit BMP-6 signaling. Inspecific embodiments, compositions of the present disclosure arescreened for their ability to inhibit BMP-6 signaling by at least 10,20, 30, 40, 50, 60, 70, 80, 90, 95, 97, 99 or 100%.

Recombinant Expression Vectors and Host Cells

Another aspect of the present disclosure pertains to vectors, preferablyexpression vectors, containing a nucleic acid encoding fusion proteinsand variants, derivatives and peptide mimetics derived therefrom of thepresent disclosure. As used herein, the term “vector” refers to anucleic acid molecule capable of transporting another nucleic acid towhich it has been linked. One type of vector is a “plasmid”, whichrefers to a linear or circular double stranded DNA loop into whichadditional DNA segments can be ligated. Another type of vector is aviral vector, wherein additional DNA segments can be ligated into theviral genome. Certain vectors are capable of autonomous replication in ahost cell into which they are introduced (e.g., bacterial vectors havinga bacterial origin of replication and episomal mammalian vectors). Othervectors (e.g., non episomal mammalian vectors) are integrated into thegenome of a host cell upon introduction into the host cell, and therebyare replicated along with the host genome. Moreover, certain vectors arecapable of directing the expression of genes to which they areoperatively linked. Such vectors are referred to herein as “expressionvectors”. In general, expression vectors of utility in recombinant DNAtechniques are often in the form of plasmids. In the presentspecification, “plasmid” and “vector” can be used interchangeably as theplasmid is the most commonly used form of vector. However, the presentdisclosure is intended to include such other forms of expressionvectors, such as viral vectors (e.g., replication defectiveretroviruses, adenoviruses and adeno associated viruses), which serveequivalent functions.

The recombinant expression vectors of the present disclosure comprise anucleic acid of the present disclosure in a form suitable for expressionof the nucleic acid in a host cell, which means that the recombinantexpression vectors include one or more regulatory sequences, selected onthe basis of the host cells to be used for expression, that isoperatively linked to the nucleic acid sequence to be expressed. Withina recombinant expression vector, “operably linked” is intended to meanthat the nucleotide sequence of interest is linked to the regulatorysequence(s) in a manner that allows for expression of the nucleotidesequence (e.g., in an in vitro transcription/translation system or in ahost cell when the vector is introduced into the host cell). The term“regulatory sequence” is intended to includes promoters, enhancers andother expression control elements (e.g., polyadenylation signals). Suchregulatory sequences are described, for example, in Goeddel; GENEEXPRESSION TECHNOLOGY: METHODS IN ENZYMOLOGY 185, Academic Press, SanDiego, Calif. (1990). Regulatory sequences include those that directconstitutive expression of a nucleotide sequence in many types of hostcell and those that direct expression of the nucleotide sequence only incertain host cells (e.g., tissue specific regulatory sequences). It willbe appreciated by those skilled in the art that the design of theexpression vector can depend on such factors as the choice of the hostcell to be transformed, the level of expression of protein desired, etc.The expression vectors of the present disclosure can be introduced intohost cells to thereby produce fusion proteins and variants, derivativesand peptide mimetics derived therefrom of the present disclosure,encoded by nucleic acids as described herein.

The recombinant expression vectors of the present disclosure can bedesigned for expression of fusion proteins and variants, derivatives andpeptide mimetics derived therefrom of the present disclosure inprokaryotic or eukaryotic cells. For example, fusion proteins andvariants, derivatives and peptide mimetics derived therefrom of thepresent disclosure can be expressed in bacterial cells such as E. coli,insect cells (using baculovirus expression vectors) yeast cells ormammalian cells. Suitable host cells are discussed further in Goeddel,GENE EXPRESSION TECHNOLOGY: METHODS IN ENZYMOLOGY 185, Academic Press,San Diego, Calif. (1990). Alternatively, the recombinant expressionvector can be transcribed and translated in vitro, for example using T7promoter regulatory sequences and T7 polymerase.

Expression of proteins in prokaryotes is most often carried out in E.coli with vectors containing constitutive or inducible promotersdirecting the expression of either fusion or non fusion proteins. Fusionvectors add a number of amino acids to a protein encoded therein,usually to the amino terminus of the recombinant protein. Such fusionvectors typically serve three purposes: (1) to increase expression ofrecombinant protein; (2) to increase the solubility of the recombinantprotein; and (3) to aid in the purification of the recombinant proteinby acting as a ligand in affinity purification. Often, in fusionexpression vectors, a proteolytic cleavage site is introduced at thejunction of the fusion moiety and the recombinant protein to enableseparation of the recombinant protein from the fusion moiety subsequentto purification of the fusion protein. Such enzymes, and their cognaterecognition sequences, include Factor Xa, thrombin and enterokinase.Typical fusion expression vectors include pGEX (Pharmacia Biotech Inc;Smith and Johnson (1988) Gene 67:31 40), pMAL (New England Biolabs,Beverly, Mass.) and pRIT5 (Pharmacia, Piscataway, N.J.) that fuseglutathione S transferase (GST), maltose E binding protein, or proteinA, respectively, to the target recombinant protein.

Examples of suitable inducible non fusion E. coli expression vectorsinclude pTrc (Amrann et al., (1988) Gene 69:301 315) and pET lld(Studier et al., GENE EXPRESSION TECHNOLOGY: METHODS IN ENZYMOLOGY 185,Academic Press, San Diego, Calif. (1990) 60 89).

One strategy to maximize recombinant protein expression in E. coli is toexpress the protein in a host bacteria with an impaired capacity toproteolytically cleave the recombinant protein. See, Gottesman, GENEEXPRESSION TECHNOLOGY: METHODS IN ENZYMOLOGY 185, Academic Press, SanDiego, Calif. (1990) 119 128. Another strategy is to alter the nucleicacid sequence of the nucleic acid to be inserted into an expressionvector so that the individual codons for each amino acid are thosepreferentially utilized in E. coli (Wada et al., (1992) Nucleic AcidsRes. 20:211:1-7, 10-13, 19-34, 45-53, 58-85, 111-113, 120, 130, 132-134and 13518). Such alteration of nucleic acid sequences of the presentdisclosure can be carried out by standard DNA synthesis techniques.

In another embodiment, the expression vector used with the compositionsof the present disclosure is a yeast expression vector. Examples ofvectors for expression in yeast S. cerevisiae include pYepSecl (Baldari,et al., (1987) EMBO J 6:229 234), pMFa (Kurjan and Herskowitz, (1982)Cell 30:933 943), pJRY88 (Schultz et al., (1987) Gene 54:113 123), pYES2(Invitrogen Corporation, San Diego, Calif.), and picZ (InVitrogen Corp,San Diego, Calif.).

Alternatively, the compositions of the present disclosure can beexpressed in insect cells using baculovirus expression vectors.Baculovirus vectors available for expression of proteins in culturedinsect cells (e.g., SF9 cells) include the pAc series (Smith et al.(1983) Mol Cell Biol 3:2156 2165) and the pVL series (Lucklow andSummers (1989) Virology 170:31 39).

In yet another embodiment, a nucleic acid of the present disclosure isexpressed in mammalian cells using a mammalian expression vector.Examples of mammalian expression vectors include pCDM8 (Seed (1987)Nature 329:840) and pMT2PC (Kaufman et al. (1987) EMBO J 6: 187 195).When used in mammalian cells, the expression vector's control functionsare often provided by viral regulatory elements. For example, commonlyused promoters are derived from polyoma, Adenovirus 2, cytomegalovirusand Simian Virus 40. For other suitable expression systems for bothprokaryotic and eukaryotic cells. See, e.g., Chapters 16 and 17 ofSambrook et al., MOLECULAR CLONING: A LABORATORY MANUAL. 2nd ed., ColdSpring Harbor Laboratory, Cold Spring Harbor Laboratory Press, ColdSpring Harbor, N.Y., 1989.

In another embodiment, the recombinant mammalian expression vector iscapable of directing expression of the nucleic acid preferentially in aparticular cell type (e.g., tissue specific regulatory elements are usedto express the nucleic acid). Tissue specific regulatory elements areknown in the art. Non limiting examples of suitable tissue specificpromoters include the albumin promoter (liver specific; Pinkert et al.(1987) Genes Dev 1:268 277), lymphoid specific promoters (Calame andEaton (1988) Adv Immunol 43:235 275), in particular promoters of T cellreceptors (Winoto and Baltimore (1989) EMBO J 8:729 733) andimmunoglobulins (Banerji et al. (1983) Cell 33:729 740; Queen andBaltimore (1983) Cell 33:741 748), neuron specific promoters (e.g., theneurofilament promoter; Byrne and Ruddle (1989) PNAS 86:5473 5477),pancreas specific promoters (Edlund et al. (1985) Science 230:912 916),and mammary gland specific promoters (e.g., milk whey promoter; U.S.Pat. No. 4,873,316 and European Application Publication No. 264, 166).Developmentally regulated promoters are also encompassed, e.g., themurine hox promoters (Kessel and Gruss (1990) Science 249:374 379) andthe α-fetoprotein promoter (Campes and Tilghman (1989) Genes Dev 3:537546).

The present disclosure further provides a recombinant expression vectorcomprising a DNA molecule of the present disclosure cloned into theexpression vector in an antisense orientation. That is, the DNA moleculeis operatively linked to a regulatory sequence in a manner that allowsfor expression (by transcription of the DNA molecule) of an RNA moleculethat is antisense to the mRNA of the fusion protein of the presentdisclosure. Regulatory sequences operatively linked to a nucleic acidcloned in the antisense orientation can be chosen that direct thecontinuous expression of the antisense RNA molecule in a variety of celltypes, for instance viral promoters and/or enhancers, or regulatorysequences can be chosen that direct constitutive, tissue specific orcell type specific expression of antisense RNA. The antisense expressionvector can be in the form of a recombinant plasmid, phagemid orattenuated virus in which antisense nucleic acids are produced under thecontrol of a high efficiency regulatory region, the activity of whichcan be determined by the cell type into which the vector is introduced.For a discussion of the regulation of gene expression using antisensegenes see Weintraub et al., “Antisense RNA as a molecular tool forgenetic analysis,” Reviews: Trends in Genetics, Vol. 1(1) 1986.

Another aspect of the present disclosure pertains to host cells intowhich a recombinant expression vector of the present disclosure has beenintroduced. The terms “host cell” and “recombinant host cell” are usedinterchangeably herein. It is understood that such terms refer not onlyto the particular subject cell but also to the progeny or potentialprogeny of such a cell. Because certain modifications may occur insucceeding generations due to either mutation or environmentalinfluences, such progeny may not, in fact, be identical to the parentcell, but are still included within the scope of the term as usedherein.

A host cell can be any prokaryotic or eukaryotic cell. For example,fusion proteins and variants, derivatives and peptide mimetics derivedtherefrom of the present disclosure can be expressed in bacterial cellssuch as E. coli, insect cells, yeast or mammalian cells (such as Chinesehamster ovary cells (CHO) or COS cells). Other suitable host cells areknown to those skilled in the art. In a preferred embodiment, the fusionprotein or variant, derivative or peptide mimetic derived therefrom ofthe present disclosure is expressed in CHO cells.

Vector DNA can be introduced into prokaryotic or eukaryotic cells viaconventional transformation or transfection techniques. As used herein,the terms “transformation” and “transfection” are intended to refer to avariety of art recognized techniques for introducing foreign nucleicacid (e.g., DNA) into a host cell, including calcium phosphate orcalcium chloride co precipitation, DEAE dextran mediated transfection,lipofection, or electroporation. Suitable methods for transforming ortransfecting host cells can be found in Sambrook, et al. (MOLECULARCLONING: A LABORATORY MANUAL. 2nd ed., Cold Spring Harbor Laboratory,Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989),and other laboratory manuals.

For stable transfection of mammalian cells, it is known that, dependingupon the expression vector and transfection technique used, only a smallfraction of cells may integrate the foreign DNA into their genome. Inorder to identify and select these integrants, a gene that encodes aselectable marker (e.g., resistance to antibiotics) is generallyintroduced into the host cells along with the gene of interest. Variousselectable markers include those that confer resistance to drugs, suchas G418, hygromycin and methotrexate. Nucleic acid encoding a selectablemarker can be introduced into a host cell on the same vector as thatencoding the composition of the present disclosure or can be introducedon a separate vector. Cells stably transfected with the introducednucleic acid can be identified by drug selection (e.g., cells that haveincorporated the selectable marker gene will survive, while the othercells die).

A host cell of the present disclosure, such as a prokaryotic oreukaryotic host cell in culture, can be used to produce (i.e., express)one or more fusion proteins and variants, derivatives and peptidemimetics derived therefrom of the present disclosure. Accordingly, thepresent disclosure further provides methods for producing one or morefusion proteins and variants, derivatives and peptide mimetics derivedtherefrom of the present disclosure using the host cells of the presentdisclosure. In one embodiment, the method comprises culturing the hostcell of disclosure (into which a recombinant expression vector encodinga composition of the present disclosure has been introduced) in asuitable medium such that the composition of the present disclosure isproduced. In another embodiment, the method further comprises isolatingthe composition of the present disclosure from the medium or the hostcell.

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present disclosure toits fullest extent. The following examples are illustrative only, andnot limiting of the remainder of the present disclosure in any waywhatsoever.

EXAMPLES Example 1. Increase in Hematocrit in Anemic Rats Treated with aHemojuvelin-Fc Fusion Protein

Rats were injection with a dose of rhamnose at 15 mg/kg. After 28 days,rats that developed joint swelling, anemia and marked leukocytosis wererandomly assigned to one of three groups. In group 1, rats were treatedwith intravenous injections of HJV.Fc (SEQ ID NO:9) at 2 mg/kg twiceweekly for 4 weeks. In group 2, rats were treated with intravenousinjections of HJV.Fc at 20 mg/kg twice weekly for 4 weeks. Group 3 ratswere untreated.

Weekly hematocrit and hemoglobin serum concentrations were measured. Atthe terminal bleed at the end of four weeks, hematocrit, hemoglobin,serum iron, splenic ferritin and liver hepcidin RNA was determined.

As shown in FIGS. 3, 5 and 6, anemic rats administered the high dose ofHJV.Fc had significantly higher serum hematocrit and serum hemoglobinthan anemic rats not administered HJV.Fc. Anemic rats administeredHJV.Fc had serum hematocrit and hemoglobin similar to non-anemic rats atthe end of four weeks of treatment. When data from the low dose HJV.Fcwas added to the high dose data, rats administered HJV.Fc hadsignificantly higher serum hematocrit and serum hemoglobin than anemicrats not administered HJV.Fc (FIG. 4). Again, anemic rats administeredHJV.Fc had serum hematocrit and hemoglobin similar to non-anemic rats atthe end of four weeks of treatment.

Example 2. Monomeric HJV.His has Low Affinity to BMP-6

FIG. 7a shows the binding of soluble human hemojuvelin with a HIS-tagbinding to human BMP6 immobilized on CM5 sensor chips by the aminecoupling method (Halbrooks 2007). Using a one-site univalent fit model,an approximate K_(d) of 33 nM is obtained. FIG. 7b , shows that solubleHJV.Fc protein can also bind to immobilized human BMP6, and that atwo-site bivalent fit model (to account for the disulfide bonded dimericnature of HJV.Fc) gives a preliminary K_(d) of approximately 13 pM,which is a much higher affinity compared to monomeric HJV.His protein.Thus, as shown in FIG. 7a , monomeric HJV.His has low affinity to BMP6.In FIG. 7b , homodimeric HJV.Fc has a significantly higher bindingaffinity to BMP6.

Example 3. HJV.Fc can Inhibit BMP6 Activity in a Dose-Dependent Manner

As shown in FIG. 8, using a cell-based bioinhibition luciferase assay,HJV.Fc can inhibit BMP6 activity in a dose-dependent manner. Hepcidinpromoter luciferase assays in a hepatoma-derived HepG2 cells werecarried out as previously described (Babitt 2007). For HJV.Fc inhibitionassays, HepG2 cells stably transfected with the hepcidin promoterluciferase reporter (cell line C33) were serum starved for 6 hours andthen incubated with 100 ng/ml BMP-6 ligand, either alone or with 0.5, 5or 10 μg/ml of HJV.Fc for 16 hours. “BRX3” and “A6” are two differentlots of HJV.Fc proteins. Moreover, as shown in FIG. 9, HJV.Fc can beprepared in an essentially pure preparation of the homodimeric proteinas demonstrated by HPLC analysis. This analytical method involved theinjection of a sample of HJV.Fc on to a BioSep 53000 chromatographycolumn (Phenomenex) with a running buffer of 100 mM Sodium Phosphate,200 mM Sodium Chloride, at pH 6.0. The flow rate was 1 ml/min anddetection was achieved at a wavelength of 280 nm.

All publications and patent applications cited in this specification areherein incorporated by reference as if each individual publication orpatent application are specifically and individually indicated to beincorporated by reference.

Although the foregoing disclosure has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, it will be readily apparent to those of ordinary skill inthe art in light of the teachings of this disclosure that certainchanges and modifications may be made thereto without departing from thespirit or scope of the appended claims.

The invention claimed is:
 1. A composition comprising a fusion proteinwherein the fusion protein comprises the sequence of SEQ ID NO:9.
 2. Thecomposition of claim 1, wherein the fusion protein is at least 98% pureas determined by size exclusion chromatography.
 3. The composition ofclaim 1, wherein the fusion protein is glycosylated.
 4. The compositionof claim 3, wherein the glycosylation pattern is a mammalianglycosylation pattern.
 5. The composition of claim 4, wherein asparagine83, asparagine 178 and/or asparagine 337 are glycosylated.
 6. Thecomposition of claim 4, wherein the glycosylation pattern is from aChinese hamster ovary (CHO) cell line.
 7. The composition of claim 1,wherein the N-terminal amino acid of the fusion protein is glutamine. 8.The composition of claim 7, wherein the N-terminus of the N-terminalamino acid of the fusion is QCKILRCNAE (SEQ ID NO: 10).
 9. Thecomposition of claim 1, wherein the composition is substantially pyrogenfree.
 10. The composition of claim 1, wherein the serum half-life of thefusion protein is at least 10 hours.
 11. The composition of claim 1,wherein the fusion protein binds to bone morphogenic protein-6 (“BMP-6”)with a KD of at least 10⁻⁷M and inhibits BMP-6 signaling.
 12. Thecomposition of claim 1, wherein the composition increases hemoglobinand/or hematocrit in a subject when administered.
 13. The composition ofclaim 1, wherein the composition increases hemoglobin and/or hematocritto at least normal levels in an anemic subject when administered to theanemic subject for one month or more.
 14. The composition of claim 1,wherein the fusion protein forms a homodimer.
 15. The composition ofclaim 14, wherein the homodimer is formed in the Fc hinge regions. 16.The composition of claim 15, wherein the homodimer is formed betweencysteines in the Fc hinge regions via a disulfide bond.
 17. A nucleicacid molecule that encodes the fusion polypeptide of claim
 1. 18. Thenucleic acid molecule of claim 17, wherein the nucleic acid moleculeencodes the fusion protein of claim 1 and comprises the sequence of SEQID NO:
 11. 19. A mammalian cell comprising the nucleic acid sequence ofclaim
 18. 20. The mammalian cell of claim 19, wherein the cell is a CHOcell.
 21. A method of increasing serum iron levels in a subject in needthereof by administering a therapeutically effective amount of thecomposition of claim 1 to the subject, thereby increasing serum ironlevels.
 22. A composition comprising a fusion protein, wherein thefusion protein comprises an N-terminal polypeptide and a C-terminalpolypeptide, wherein the N-terminal polypeptide comprises the sequenceof SEQ ID NO: 1 and wherein the C-terminal peptide comprises a sequenceselected from the group consisting of SEQ ID NOs: 3, 4, 5, 6, and
 7. 23.The composition of claim 22, wherein the fusion protein is at least 98%pure as determined by size exclusion chromatography.
 24. The compositionof claim 22, wherein the fusion protein is glycosylated.
 25. Thecomposition of claim 24, wherein the glycosylation pattern is amammalian glycosylation pattern.
 26. The composition of claim 25,wherein the glycosylation pattern is from a Chinese hamster ovary (CHO)cell line.
 27. The composition of claim 22, wherein the N-terminal aminoacid of the fusion protein is glutamine.
 28. The composition of claim27, wherein the N-terminus of the N-terminal amino acid of the fusion isQCKILRCNAE (SEQ ID NO: 10).
 29. The composition of claim 22, wherein thecomposition is substantially pyrogen free.
 30. The composition of claim22, wherein the serum half-life of the fusion protein is at least 10hours.
 31. The composition of claim 22, wherein the fusion protein bindsto bone morphogenic protein-6 (“BMP-6”) with a KD of at least 10⁻⁷M andinhibits BMP-6 signaling.
 32. The composition of claim 22, wherein thecomposition increases hematocrit in a subject when administered.
 33. Thecomposition of claim 22, wherein the composition increases hematocrit toat least normal levels in an anemic subject when administered to theanemic subject for one month or more.
 34. The composition of claim 22,wherein the fusion protein forms a homodimer.
 35. A nucleic acidmolecule that encodes the fusion protein of claim
 22. 36. The nucleicacid of claim 35, wherein the nucleic acid molecule encodes the fusionprotein of claim 22 and comprises the sequence of SEQ ID NO:
 11. 37. Amammalian cell comprising the nucleic acid sequence of claim
 35. 38. Themammalian cell of claim 37, wherein the cell is a CHO cell.
 39. A methodof increasing serum iron levels and/or improving anemia in a subject inneed thereof by administering a therapeutically effective amount of thecomposition of claim 22 to the subject, thereby increasing serum ironlevels and/or improving anemia.